diff --git a/source/blender/blenkernel/intern/attribute_storage.cc b/source/blender/blenkernel/intern/attribute_storage.cc
index 7c1278b433d..72eb7ef8d16 100644
--- a/source/blender/blenkernel/intern/attribute_storage.cc
+++ b/source/blender/blenkernel/intern/attribute_storage.cc
@@ -634,19 +634,19 @@ void AttributeStorage::blend_write(BlendWriter &writer,
     switch (AttrStorageType(attr_dna.storage_type)) {
       case AttrStorageType::Single: {
         ::AttributeSingle *single_dna = static_cast<::AttributeSingle *>(attr_dna.data);
-        BLO_write_struct(&writer, AttributeSingle, single_dna);
         write_shared_array(
             writer, AttrType(attr_dna.data_type), single_dna->data, 1, single_dna->sharing_info);
+        BLO_write_struct(&writer, AttributeSingle, single_dna);
         break;
       }
       case AttrStorageType::Array: {
         ::AttributeArray *array_dna = static_cast<::AttributeArray *>(attr_dna.data);
-        BLO_write_struct(&writer, AttributeArray, array_dna);
         write_shared_array(writer,
                            AttrType(attr_dna.data_type),
                            array_dna->data,
                            array_dna->size,
                            array_dna->sharing_info);
+        BLO_write_struct(&writer, AttributeArray, array_dna);
         break;
       }
     }
diff --git a/source/blender/blenkernel/intern/curves.cc b/source/blender/blenkernel/intern/curves.cc
index b7f22cd9748..01563c4b217 100644
--- a/source/blender/blenkernel/intern/curves.cc
+++ b/source/blender/blenkernel/intern/curves.cc
@@ -122,6 +122,9 @@ static void curves_blend_write(BlendWriter *writer, ID *id, const void *id_addre
   blender::bke::CurvesGeometry::BlendWriteData write_data(scope);
   curves->geometry.wrap().blend_write_prepare(write_data);
 
+  BLO_write_shared_tag(writer, curves->geometry.curve_offsets);
+  BLO_write_shared_tag(writer, curves->geometry.custom_knots);
+
   /* Write LibData */
   BLO_write_id_struct(writer, Curves, id_address, &curves->id);
   BKE_id_blend_write(writer, &curves->id);
diff --git a/source/blender/blenkernel/intern/customdata.cc b/source/blender/blenkernel/intern/customdata.cc
index 8bb9a50ebd6..7064e1ccb1e 100644
--- a/source/blender/blenkernel/intern/customdata.cc
+++ b/source/blender/blenkernel/intern/customdata.cc
@@ -5163,9 +5163,6 @@ void CustomData_blend_write(BlendWriter *writer,
     CustomData_external_write(data, id, cddata_mask, count, 0);
   }
 
-  BLO_write_struct_array_at_address(
-      writer, CustomDataLayer, data->totlayer, data->layers, layers_to_write.data());
-
   for (const CustomDataLayer &layer : layers_to_write) {
     const size_t size_in_bytes = CustomData_sizeof(eCustomDataType(layer.type)) * count;
     BLO_write_shared(writer, layer.data, size_in_bytes, layer.sharing_info, [&]() {
@@ -5173,6 +5170,9 @@ void CustomData_blend_write(BlendWriter *writer,
     });
   }
 
+  BLO_write_struct_array_at_address(
+      writer, CustomDataLayer, data->totlayer, data->layers, layers_to_write.data());
+
   if (data->external) {
     BLO_write_struct(writer, CustomDataExternal, data->external);
   }
diff --git a/source/blender/blenkernel/intern/mesh.cc b/source/blender/blenkernel/intern/mesh.cc
index 70257281151..32b73a91d1b 100644
--- a/source/blender/blenkernel/intern/mesh.cc
+++ b/source/blender/blenkernel/intern/mesh.cc
@@ -395,6 +395,8 @@ static void mesh_blend_write(BlendWriter *writer, ID *id, const void *id_address
   const blender::bke::MeshRuntime *mesh_runtime = mesh->runtime;
   mesh->runtime = nullptr;
 
+  BLO_write_shared_tag(writer, mesh->face_offset_indices);
+
   BLO_write_id_struct(writer, Mesh, id_address, &mesh->id);
   BKE_id_blend_write(writer, &mesh->id);
 
diff --git a/source/blender/blenkernel/intern/packedFile.cc b/source/blender/blenkernel/intern/packedFile.cc
index 0eb44efcca2..287dbc59a34 100644
--- a/source/blender/blenkernel/intern/packedFile.cc
+++ b/source/blender/blenkernel/intern/packedFile.cc
@@ -974,10 +974,10 @@ void BKE_packedfile_blend_write(BlendWriter *writer, const PackedFile *pf)
   if (pf == nullptr) {
     return;
   }
-  BLO_write_struct(writer, PackedFile, pf);
   BLO_write_shared(writer, pf->data, pf->size, pf->sharing_info, [&]() {
     BLO_write_raw(writer, pf->size, pf->data);
   });
+  BLO_write_struct(writer, PackedFile, pf);
 }
 
 void BKE_packedfile_blend_read(BlendDataReader *reader, PackedFile **pf_p, StringRefNull filepath)
diff --git a/source/blender/blenloader/BLO_read_write.hh b/source/blender/blenloader/BLO_read_write.hh
index 620fd62b413..52420564a36 100644
--- a/source/blender/blenloader/BLO_read_write.hh
+++ b/source/blender/blenloader/BLO_read_write.hh
@@ -222,6 +222,10 @@ void BLO_write_string(BlendWriter *writer, const char *data_ptr);
  * user count of the sharing-info is increased making the data immutable. The provided callback
  * should serialize the potentially shared data. It is only called when necessary.
  *
+ * This should be called before the data is referenced in other written data (there is an assert
+ * that checks for this). If that's not possible, at least #BLO_write_shared_tag needs to be called
+ * before the pointer is first written.
+ *
  * \param approximate_size_in_bytes: Used to be able to approximate how large the undo step is in
  * total.
  * \param write_fn: Use the #BlendWrite to serialize the potentially shared data.
@@ -232,6 +236,11 @@ void BLO_write_shared(BlendWriter *writer,
                       const blender::ImplicitSharingInfo *sharing_info,
                       blender::FunctionRef<void()> write_fn);
 
+/**
+ * Needs to be called if the pointer is somewhere written before the call to #BLO_write_shared.
+ */
+void BLO_write_shared_tag(BlendWriter *writer, const void *data);
+
 /**
  * Sometimes different data is written depending on whether the file is saved to disk or used for
  * undo. This function returns true when the current file-writing is done for undo.
diff --git a/source/blender/blenloader/intern/writefile.cc b/source/blender/blenloader/intern/writefile.cc
index 08efd66b01b..57518f0f511 100644
--- a/source/blender/blenloader/intern/writefile.cc
+++ b/source/blender/blenloader/intern/writefile.cc
@@ -830,6 +830,9 @@ static void write_bhead(WriteData *wd, const BHead &bhead)
   mywrite(wd, &bh, sizeof(bh));
 }
 
+/** This bit is used to mark address ids that use implicit sharing during undo. */
+constexpr uint64_t implicit_sharing_address_id_flag = uint64_t(1) << 63;
+
 static uint64_t stable_id_from_hint(const uint64_t hint)
 {
   /* Add a stride. This is not strictly necessary but may help with debugging later on because it's
@@ -839,6 +842,8 @@ static uint64_t stable_id_from_hint(const uint64_t hint)
     /* Null values are reserved for nullptr. */
     stable_id = (1 << 4);
   }
+  /* Remove the first bit as it reserved for pointers for implicit sharing.*/
+  stable_id &= ~implicit_sharing_address_id_flag;
   return stable_id;
 }
 
@@ -857,6 +862,27 @@ static uint64_t get_next_stable_address_id(WriteData &wd)
   return stable_id;
 }
 
+/**
+ * When writing an undo step, implicitly shared pointers do not use stable-pointers because that
+ * would lead to incorrect detection if a data-block has been changed between undo steps. That's
+ * because different shared data could be mapped to the same stable pointer, leading to
+ * #is_memchunk_identical to being true even if the referenced data is actually different.
+ *
+ * Another way to look at it is that implicit-sharing is a system for stable pointers (at runtime)
+ * itself. So it does not need an additional layer of stable pointers on top.
+ */
+static uint64_t get_address_id_for_implicit_sharing_data(const void *data)
+{
+  BLI_assert(data != nullptr);
+  uint64_t address_id = uint64_t(data);
+  /* Adding this bit so that it never overlap with an id generated by #stable_id_from_hint.
+   * Assuming that the given pointer is an actual pointer, it will stay unique when the
+   * #implicit_sharing_address_id_flag bit is set. That's because the upper bits of the pointer
+   * are effectively unused nowadays. */
+  address_id |= implicit_sharing_address_id_flag;
+  return address_id;
+}
+
 static uint64_t get_address_id_int(WriteData &wd, const void *address)
 {
   if (address == nullptr) {
@@ -2248,6 +2274,21 @@ void BLO_write_string(BlendWriter *writer, const char *data_ptr)
   }
 }
 
+void BLO_write_shared_tag(BlendWriter *writer, const void *data)
+{
+  if (!data) {
+    return;
+  }
+  if (!BLO_write_is_undo(writer)) {
+    return;
+  }
+  const uint64_t address_id = get_address_id_for_implicit_sharing_data(data);
+  /* Check that the pointer has not been written before it was tagged as being shared. */
+  BLI_assert(writer->wd->stable_address_ids.pointer_map.lookup_default(data, address_id) ==
+             address_id);
+  writer->wd->stable_address_ids.pointer_map.add(data, address_id);
+}
+
 void BLO_write_shared(BlendWriter *writer,
                       const void *data,
                       const size_t approximate_size_in_bytes,
@@ -2257,6 +2298,9 @@ void BLO_write_shared(BlendWriter *writer,
   if (data == nullptr) {
     return;
   }
+  if (sharing_info) {
+    BLO_write_shared_tag(writer, data);
+  }
   const uint64_t address_id = get_address_id_int(*writer->wd, data);
   if (BLO_write_is_undo(writer)) {
     MemFile &memfile = *writer->wd->mem.written_memfile;
diff --git a/source/blender/modifiers/intern/MOD_correctivesmooth.cc b/source/blender/modifiers/intern/MOD_correctivesmooth.cc
index bfda2f6f8ec..4792daf939b 100644
--- a/source/blender/modifiers/intern/MOD_correctivesmooth.cc
+++ b/source/blender/modifiers/intern/MOD_correctivesmooth.cc
@@ -792,8 +792,6 @@ static void blend_write(BlendWriter *writer, const ID *id_owner, const ModifierD
     }
   }
 
-  BLO_write_struct_at_address(writer, CorrectiveSmoothModifierData, md, &csmd);
-
   if (csmd.bind_coords != nullptr) {
     BLO_write_shared(writer,
                      csmd.bind_coords,
@@ -804,6 +802,8 @@ static void blend_write(BlendWriter *writer, const ID *id_owner, const ModifierD
                            writer, csmd.bind_coords_num, (const float *)csmd.bind_coords);
                      });
   }
+
+  BLO_write_struct_at_address(writer, CorrectiveSmoothModifierData, md, &csmd);
 }
 
 static void blend_read(BlendDataReader *reader, ModifierData *md)
diff --git a/source/blender/modifiers/intern/MOD_laplaciandeform.cc b/source/blender/modifiers/intern/MOD_laplaciandeform.cc
index f85f5fe9fc0..4c73d9a300f 100644
--- a/source/blender/modifiers/intern/MOD_laplaciandeform.cc
+++ b/source/blender/modifiers/intern/MOD_laplaciandeform.cc
@@ -832,14 +832,14 @@ static void blend_write(BlendWriter *writer, const ID *id_owner, const ModifierD
     }
   }
 
-  BLO_write_struct_at_address(writer, LaplacianDeformModifierData, md, &lmd);
-
   if (lmd.vertexco != nullptr) {
     BLO_write_shared(
         writer, lmd.vertexco, sizeof(float[3]) * lmd.verts_num, lmd.vertexco_sharing_info, [&]() {
           BLO_write_float3_array(writer, lmd.verts_num, lmd.vertexco);
         });
   }
+
+  BLO_write_struct_at_address(writer, LaplacianDeformModifierData, md, &lmd);
 }
 
 static void blend_read(BlendDataReader *reader, ModifierData *md)
diff --git a/source/blender/modifiers/intern/MOD_meshdeform.cc b/source/blender/modifiers/intern/MOD_meshdeform.cc
index be94ee93a06..9f387bbad2b 100644
--- a/source/blender/modifiers/intern/MOD_meshdeform.cc
+++ b/source/blender/modifiers/intern/MOD_meshdeform.cc
@@ -563,8 +563,6 @@ static void blend_write(BlendWriter *writer, const ID *id_owner, const ModifierD
 
   const int size = mmd.dyngridsize;
 
-  BLO_write_struct_at_address(writer, MeshDeformModifierData, md, &mmd);
-
   BLO_write_shared(writer,
                    mmd.bindinfluences,
                    sizeof(MDefInfluence) * mmd.influences_num,
@@ -609,6 +607,8 @@ static void blend_write(BlendWriter *writer, const ID *id_owner, const ModifierD
                    sizeof(MDefInfluence) * mmd.verts_num,
                    mmd.dynverts_sharing_info,
                    [&]() { BLO_write_int32_array(writer, mmd.verts_num, mmd.dynverts); });
+
+  BLO_write_struct_at_address(writer, MeshDeformModifierData, md, &mmd);
 }
 
 static void blend_read(BlendDataReader *reader, ModifierData *md)
diff --git a/source/blender/modifiers/intern/MOD_surfacedeform.cc b/source/blender/modifiers/intern/MOD_surfacedeform.cc
index 2a77dd08721..32f7ed20b18 100644
--- a/source/blender/modifiers/intern/MOD_surfacedeform.cc
+++ b/source/blender/modifiers/intern/MOD_surfacedeform.cc
@@ -1652,8 +1652,6 @@ static void blend_write(BlendWriter *writer, const ID *id_owner, const ModifierD
     }
   }
 
-  BLO_write_struct_at_address(writer, SurfaceDeformModifierData, md, &smd);
-
   if (smd.verts != nullptr) {
     BLO_write_shared(
         writer, smd.verts, sizeof(SDefVert) * smd.bind_verts_num, smd.verts_sharing_info, [&]() {
@@ -1684,6 +1682,8 @@ static void blend_write(BlendWriter *writer, const ID *id_owner, const ModifierD
           }
         });
   }
+
+  BLO_write_struct_at_address(writer, SurfaceDeformModifierData, md, &smd);
 }
 
 static void blend_read(BlendDataReader *reader, ModifierData *md)