diff --git a/src/application/services/HeadingSyncMarkerService.test.ts b/src/application/services/HeadingSyncMarkerService.test.ts
index 2a6207b..3a995fe 100644
--- a/src/application/services/HeadingSyncMarkerService.test.ts
+++ b/src/application/services/HeadingSyncMarkerService.test.ts
@@ -12,11 +12,11 @@ describe("HeadingSyncMarkerService", () => {
     const nextContent = service.apply(
       {
         filePath: "notes/example.md",
-        sourceContent: ["#### Prompt", "Answer", "", "### Next"].join("\n"),
+        sourceContent: ["#### Prompt", "Answer", "", "", "### Next"].join("\n"),
         headingLine: 1,
         blockStartLine: 1,
         bodyStartLine: 2,
-        blockEndLine: 3,
+        blockEndLine: 4,
         contentEndLine: 2,
         headingLevel: 4,
         headingText: "Prompt",
@@ -24,7 +24,7 @@ describe("HeadingSyncMarkerService", () => {
       123,
     );
 
-    expect(nextContent).toBe(["#### Prompt", "Answer", "<!-- AHS:123 -->", "", "### Next"].join("\n"));
+    expect(nextContent).toBe(["#### Prompt", "Answer", "<!-- AHS:123 -->", "", "", "### Next"].join("\n"));
   });
 
   it("writes the marker right after the heading when the block body is empty", () => {
@@ -43,18 +43,18 @@ describe("HeadingSyncMarkerService", () => {
       456,
     );
 
-    expect(nextContent).toBe(["#### Prompt", "<!-- AHS:456 -->", "### Next"].join("\n"));
+    expect(nextContent).toBe(["#### Prompt", "<!-- AHS:456 -->", "", "", "### Next"].join("\n"));
   });
 
   it("replaces an existing marker without moving past the next heading", () => {
     const nextContent = service.apply(
       {
         filePath: "notes/example.md",
-        sourceContent: ["#### Prompt", "Answer", "<!-- AHS:123 -->", "### Next"].join("\n"),
+        sourceContent: ["#### Prompt", "Answer", "<!-- AHS:123 -->", "", "", "### Next"].join("\n"),
         headingLine: 1,
         blockStartLine: 1,
         bodyStartLine: 2,
-        blockEndLine: 3,
+        blockEndLine: 5,
         contentEndLine: 2,
         markerLine: 3,
         headingLevel: 4,
@@ -63,7 +63,7 @@ describe("HeadingSyncMarkerService", () => {
       789,
     );
 
-    expect(nextContent).toBe(["#### Prompt", "Answer", "<!-- AHS:789 -->", "### Next"].join("\n"));
+    expect(nextContent).toBe(["#### Prompt", "Answer", "<!-- AHS:789 -->", "", "", "### Next"].join("\n"));
   });
 
   it("applies multiple writes in one file from bottom to top", () => {
@@ -71,6 +71,7 @@ describe("HeadingSyncMarkerService", () => {
       "#### Top",
       "Top answer",
       "",
+      "",
       "#### Bottom",
       "Bottom answer",
     ].join("\n");
@@ -86,7 +87,7 @@ describe("HeadingSyncMarkerService", () => {
           headingLine: 1,
           blockStartLine: 1,
           bodyStartLine: 2,
-          blockEndLine: 3,
+          blockEndLine: 4,
           contentEndLine: 2,
           headingLevel: 4,
           headingText: "Top",
@@ -101,11 +102,11 @@ describe("HeadingSyncMarkerService", () => {
         location: {
           filePath: "notes/example.md",
           sourceContent,
-          headingLine: 4,
-          blockStartLine: 4,
-          bodyStartLine: 5,
-          blockEndLine: 5,
-          contentEndLine: 5,
+          headingLine: 5,
+          blockStartLine: 5,
+          bodyStartLine: 6,
+          blockEndLine: 6,
+          contentEndLine: 6,
           headingLevel: 4,
           headingText: "Bottom",
         },
@@ -119,6 +120,7 @@ describe("HeadingSyncMarkerService", () => {
       "Top answer",
       "<!-- AHS:111 -->",
       "",
+      "",
       "#### Bottom",
       "Bottom answer",
       "<!-- AHS:222 -->",
@@ -131,6 +133,7 @@ describe("HeadingSyncMarkerService", () => {
       "Body 1",
       "<!-- AHS:42 -->",
       "",
+      "",
       "#### Second",
       "Body 2",
     ].join("\n");
@@ -146,7 +149,7 @@ describe("HeadingSyncMarkerService", () => {
           headingLine: 1,
           blockStartLine: 1,
           bodyStartLine: 2,
-          blockEndLine: 3,
+          blockEndLine: 5,
           contentEndLine: 2,
           markerLine: 3,
           headingLevel: 4,
@@ -162,11 +165,11 @@ describe("HeadingSyncMarkerService", () => {
         location: {
           filePath: "notes/example.md",
           sourceContent,
-          headingLine: 5,
-          blockStartLine: 5,
-          bodyStartLine: 6,
-          blockEndLine: 6,
-          contentEndLine: 6,
+          headingLine: 6,
+          blockStartLine: 6,
+          bodyStartLine: 7,
+          blockEndLine: 7,
+          contentEndLine: 7,
           headingLevel: 4,
           headingText: "Second",
         },
@@ -180,9 +183,10 @@ describe("HeadingSyncMarkerService", () => {
       "Body 1",
       "<!-- AHS:9001 -->",
       "",
+      "",
       "#### Second",
       "Body 2",
       "<!-- AHS:9002 -->",
     ].join("\n"));
   });
-});
\ No newline at end of file
+});
diff --git a/src/application/services/HeadingSyncMarkerService.ts b/src/application/services/HeadingSyncMarkerService.ts
index 4bceef4..b85980b 100644
--- a/src/application/services/HeadingSyncMarkerService.ts
+++ b/src/application/services/HeadingSyncMarkerService.ts
@@ -93,11 +93,32 @@ export class HeadingSyncMarkerService {
       throw new HeadingSyncMarkerBatchError(`Cannot write AHS marker outside the heading block in ${location.filePath}.`);
     }
 
+    const removalIndexes = new Set<number>();
     if (location.markerLine) {
-      lines.splice(location.markerLine - 1, 1);
+      removalIndexes.add(location.markerLine - 1);
     }
 
-    lines.splice(location.contentEndLine, 0, this.create(noteId).raw);
+    for (let lineIndex = location.contentEndLine; lineIndex < location.blockEndLine; lineIndex += 1) {
+      if (!(lines[lineIndex] ?? "").trim()) {
+        removalIndexes.add(lineIndex);
+      }
+    }
+
+    const sortedRemovals = [...removalIndexes].sort((left, right) => right - left);
+    const insertionIndex = location.contentEndLine - [...removalIndexes].filter((lineIndex) => lineIndex < location.contentEndLine).length;
+
+    for (const lineIndex of sortedRemovals) {
+      lines.splice(lineIndex, 1);
+    }
+
+    lines.splice(insertionIndex, 0, this.create(noteId).raw);
+    while (insertionIndex + 1 < lines.length && !(lines[insertionIndex + 1] ?? "").trim()) {
+      lines.splice(insertionIndex + 1, 1);
+    }
+
+    if (insertionIndex + 1 < lines.length) {
+      lines.splice(insertionIndex + 1, 0, "", "");
+    }
   }
 
   create(noteId: number): HeadingSyncMarker {
@@ -107,4 +128,4 @@ export class HeadingSyncMarkerService {
       lineIndex: -1,
     };
   }
-}
\ No newline at end of file
+}
diff --git a/src/application/services/ManualSyncService.ts b/src/application/services/ManualSyncService.ts
index a217b8d..2a4a1c2 100644
--- a/src/application/services/ManualSyncService.ts
+++ b/src/application/services/ManualSyncService.ts
@@ -414,6 +414,7 @@ export class ManualSyncService {
           syncKey: block.syncKey,
           filePath: block.filePath,
           blockStartLine: block.blockStartLine,
+          contentEndLine: block.contentEndLine,
           blockEndLine: block.blockEndLine,
           markerLine: block.markerLine,
           markerIndent: block.markerIndent,
diff --git a/src/application/services/QaGroupSyncService.ts b/src/application/services/QaGroupSyncService.ts
index f785b9d..f36df06 100644
--- a/src/application/services/QaGroupSyncService.ts
+++ b/src/application/services/QaGroupSyncService.ts
@@ -179,6 +179,7 @@ export class QaGroupSyncService {
           syncKey: block.syncKey,
           filePath: block.filePath,
           blockStartLine: block.blockStartLine,
+          contentEndLine: block.contentEndLine,
           blockEndLine: block.blockEndLine,
           markerLine: block.markerLine,
           markerIndent: block.markerIndent,
diff --git a/src/domain/manual-sync/services/CardMarkerService.test.ts b/src/domain/manual-sync/services/CardMarkerService.test.ts
index a8fae88..309de7f 100644
--- a/src/domain/manual-sync/services/CardMarkerService.test.ts
+++ b/src/domain/manual-sync/services/CardMarkerService.test.ts
@@ -15,7 +15,7 @@ describe("CardMarkerService", () => {
 
   it("writes multiple markers bottom-up in a single file", () => {
     const service = new CardMarkerService();
-    const sourceContent = ["#### Top", "Body 1", "", "#### Bottom", "Body 2"].join("\n");
+    const sourceContent = ["#### Top", "Body 1", "", "", "#### Bottom", "Body 2"].join("\n");
 
     const nextContent = service.applyBatch(sourceContent, [
       {
@@ -23,15 +23,15 @@ describe("CardMarkerService", () => {
         noteId: 11,
         blockStartLine: 1,
         contentEndLine: 2,
-        blockEndLine: 3,
+        blockEndLine: 4,
         sourceContent,
       },
       {
         filePath: "notes/example.md",
         noteId: 22,
-        blockStartLine: 4,
-        contentEndLine: 5,
-        blockEndLine: 5,
+        blockStartLine: 5,
+        contentEndLine: 6,
+        blockEndLine: 6,
         sourceContent,
       },
     ]);
@@ -41,9 +41,10 @@ describe("CardMarkerService", () => {
       "Body 1",
       "<!--ID: 11-->",
       "",
+      "",
       "#### Bottom",
       "Body 2",
       "<!--ID: 22-->",
     ].join("\n"));
   });
-});
\ No newline at end of file
+});
diff --git a/src/domain/manual-sync/services/CardMarkerService.ts b/src/domain/manual-sync/services/CardMarkerService.ts
index b95fc84..1834269 100644
--- a/src/domain/manual-sync/services/CardMarkerService.ts
+++ b/src/domain/manual-sync/services/CardMarkerService.ts
@@ -94,6 +94,10 @@ export class CardMarkerService {
         throw new CardMarkerError(`Cannot replace marker outside the heading block in ${write.filePath}.`);
       }
 
+      if (write.contentEndLine < write.blockStartLine || write.contentEndLine > write.blockEndLine) {
+        throw new CardMarkerError(`Cannot write marker outside the content range in ${write.filePath}.`);
+      }
+
       if (seenBlocks.has(write.blockStartLine)) {
         throw new CardMarkerError(`Duplicate marker write detected for block ${write.blockStartLine} in ${write.filePath}.`);
       }
@@ -108,10 +112,31 @@ export class CardMarkerService {
       throw new CardMarkerError(`Cannot write marker outside the heading block in ${write.filePath}.`);
     }
 
+    const removalIndexes = new Set<number>();
     if (write.markerLine !== undefined) {
-      lines.splice(write.markerLine - 1, 1);
+      removalIndexes.add(write.markerLine - 1);
     }
 
-    lines.splice(write.contentEndLine, 0, `${write.markerIndent ?? ""}${this.create(write.noteId).raw}`);
+    for (let lineIndex = write.contentEndLine; lineIndex < write.blockEndLine; lineIndex += 1) {
+      if (!(lines[lineIndex] ?? "").trim()) {
+        removalIndexes.add(lineIndex);
+      }
+    }
+
+    const sortedRemovals = [...removalIndexes].sort((left, right) => right - left);
+    const insertionIndex = write.contentEndLine - [...removalIndexes].filter((lineIndex) => lineIndex < write.contentEndLine).length;
+
+    for (const lineIndex of sortedRemovals) {
+      lines.splice(lineIndex, 1);
+    }
+
+    lines.splice(insertionIndex, 0, `${write.markerIndent ?? ""}${this.create(write.noteId).raw}`);
+    while (insertionIndex + 1 < lines.length && !(lines[insertionIndex + 1] ?? "").trim()) {
+      lines.splice(insertionIndex + 1, 1);
+    }
+
+    if (insertionIndex + 1 < lines.length) {
+      lines.splice(insertionIndex + 1, 0, "", "");
+    }
   }
-}
\ No newline at end of file
+}
diff --git a/src/domain/manual-sync/services/GroupMarkerService.test.ts b/src/domain/manual-sync/services/GroupMarkerService.test.ts
index a02d8d7..0e6ebb8 100644
--- a/src/domain/manual-sync/services/GroupMarkerService.test.ts
+++ b/src/domain/manual-sync/services/GroupMarkerService.test.ts
@@ -12,15 +12,20 @@ describe("GroupMarkerService", () => {
       "  <!--ID: 42-->",
       "- Beta",
       "  - Second answer",
+      "",
+      "",
       "<!--GI:n=42;i=item_a:1;f=2,3,4,5,6,7,8,9,10,11,12-->",
+      "",
+      "#### Next heading",
     ].join("\n");
 
     const nextContent = service.applyBatch(sourceContent, [{
       syncKey: "notes/example.md\u0000group\u00001\u0000hash",
       filePath: "notes/example.md",
       blockStartLine: 1,
-      blockEndLine: 7,
-      markerLine: 7,
+      contentEndLine: 6,
+      blockEndLine: 9,
+      markerLine: 9,
       noteId: 42,
       itemToSlot: { item_a: 1, item_b: 2 },
       freeSlots: [3, 4, 5, 6, 7, 8, 9, 10, 11, 12],
@@ -28,6 +33,16 @@ describe("GroupMarkerService", () => {
     }]);
 
     expect(nextContent).not.toContain("<!--ID: 42-->");
-    expect(nextContent.split("\n").at(-1)).toBe("<!--GI:n=42;i=item_a:1,item_b:2;f=3,4,5,6,7,8,9,10,11,12-->");
+    expect(nextContent).toBe([
+      "#### Concepts #anki-list",
+      "- Alpha",
+      "  - First answer",
+      "- Beta",
+      "  - Second answer",
+      "<!--GI:n=42;i=item_a:1,item_b:2;f=3,4,5,6,7,8,9,10,11,12-->",
+      "",
+      "",
+      "#### Next heading",
+    ].join("\n"));
   });
-});
\ No newline at end of file
+});
diff --git a/src/domain/manual-sync/services/GroupMarkerService.ts b/src/domain/manual-sync/services/GroupMarkerService.ts
index a3e2f8f..6e494e5 100644
--- a/src/domain/manual-sync/services/GroupMarkerService.ts
+++ b/src/domain/manual-sync/services/GroupMarkerService.ts
@@ -9,6 +9,7 @@ export interface GroupMarkerWriteRequest {
   syncKey: string;
   filePath: string;
   blockStartLine: number;
+  contentEndLine: number;
   blockEndLine: number;
   markerLine?: number;
   markerIndent?: string;
@@ -114,6 +115,10 @@ export class GroupMarkerService {
         throw new GroupMarkerError(`Cannot replace GI marker outside the heading block in ${write.filePath}.`);
       }
 
+      if (write.contentEndLine < write.blockStartLine || write.contentEndLine > write.blockEndLine) {
+        throw new GroupMarkerError(`Cannot place GI marker outside the content range in ${write.filePath}.`);
+      }
+
       if (seenBlocks.has(write.blockStartLine)) {
         throw new GroupMarkerError(`Duplicate GI marker write detected for block ${write.blockStartLine} in ${write.filePath}.`);
       }
@@ -145,15 +150,27 @@ export class GroupMarkerService {
       uniqueRemovals.add(write.markerLine - 1);
     }
 
+    for (let lineIndex = write.contentEndLine; lineIndex < write.blockEndLine; lineIndex += 1) {
+      if (!(lines[lineIndex] ?? "").trim()) {
+        uniqueRemovals.add(lineIndex);
+      }
+    }
+
     const removalIndexes = [...uniqueRemovals].sort((left, right) => right - left);
-    const removalsWithinBlock = [...uniqueRemovals].filter((lineIndex) => lineIndex <= write.blockEndLine - 1).length;
-    const insertionIndex = write.blockEndLine - removalsWithinBlock;
+    const insertionIndex = write.contentEndLine - [...uniqueRemovals].filter((lineIndex) => lineIndex < write.contentEndLine).length;
 
     for (const lineIndex of removalIndexes) {
       lines.splice(lineIndex, 1);
     }
 
     lines.splice(insertionIndex, 0, `${write.markerIndent ?? ""}${serializeGroupMarker(write.noteId, write.itemToSlot, write.freeSlots)}`);
+    while (insertionIndex + 1 < lines.length && !(lines[insertionIndex + 1] ?? "").trim()) {
+      lines.splice(insertionIndex + 1, 1);
+    }
+
+    if (insertionIndex + 1 < lines.length) {
+      lines.splice(insertionIndex + 1, 0, "", "");
+    }
   }
 }
 
@@ -266,4 +283,4 @@ function collectLegacyIdMarkerLineIndexes(lines: string[], blockStartLine: numbe
 
 function compareMarkerEntry(left: [string, number], right: [string, number]): number {
   return left[1] - right[1] || left[0].localeCompare(right[0]);
-}
\ No newline at end of file
+}