diff --git a/CHANGELOG.md b/CHANGELOG.md
index cd57f3e2..344b066d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -11,6 +11,7 @@ CHANGELOG for FlatCAM beta
 
 - Cutout Plugin - improved the functionality in Manual mode: depending on the state of the Shape parameter different types of cutout manual geometry is generated
 - fixed a bug in the Editors when trying to launch the Editor without an object selected
+- Markers Plugin - fixed issue when adding existing markers to an external Geometry object
 
 31.10.2021
 
diff --git a/appPlugins/ToolMarkers.py b/appPlugins/ToolMarkers.py
index f47c7e45..ce866788 100644
--- a/appPlugins/ToolMarkers.py
+++ b/appPlugins/ToolMarkers.py
@@ -662,9 +662,11 @@ class ToolMarkers(AppTool):
                 tool_found = tool
                 break
 
-        geo_buff_list = []
         if tool_found:
-            new_tools[tool_found]['solid_geometry'] += marker_geometry
+            if isinstance(new_tools[tool_found]['solid_geometry'], list):
+                new_tools[tool_found]['solid_geometry'] += marker_geometry
+            else:
+                new_tools[tool_found]['solid_geometry'] = [new_tools[tool_found]['solid_geometry'], marker_geometry]
         else:
             obj_tools = list(new_tools.keys())
             if obj_tools:
@@ -696,23 +698,13 @@ class ToolMarkers(AppTool):
 
         s_list = []
         if new_geo_obj.solid_geometry:
-            if isinstance(new_geo_obj.solid_geometry, MultiPolygon):
-                work_geo = new_geo_obj.solid_geometry.geoms
-            else:
-                work_geo = new_geo_obj.solid_geometry
-            try:
-                for poly in work_geo:
-                    s_list.append(poly)
-            except TypeError:
-                s_list.append(work_geo)
-
-        geo_buff_list = flatten_shapely_geometry(geo_buff_list)
+            s_list = flatten_shapely_geometry(new_geo_obj.solid_geometry)
 
         try:
-            for poly in geo_buff_list + marker_geometry:
-                s_list.append(poly)
+            for g_el in marker_geometry:
+                s_list.append(g_el)
         except TypeError:
-            s_list.append(geo_buff_list)
+            s_list.append(marker_geometry)
 
         def initialize(geo_obj, app_obj):
             geo_obj.options = LoudDict()
@@ -722,11 +714,11 @@ class ToolMarkers(AppTool):
 
             # Propagate options
             geo_obj.options["tools_mill_tooldia"] = app_obj.defaults["tools_mill_tooldia"]
-            geo_obj.solid_geometry = flatten_shapely_geometry(unary_union(s_list))
+            geo_obj.solid_geometry = flatten_shapely_geometry(s_list)
 
-            geo_obj.multitool = False
-            geo_obj.multigeo = False
-            geo_obj.tools = new_tools
+            geo_obj.multitool = True
+            geo_obj.multigeo = True
+            geo_obj.tools = deepcopy(new_tools)
 
         ret = self.app.app_obj.new_object('geometry', outname, initialize, plot=True, autoselected=False)
 
diff --git a/camlib.py b/camlib.py
index 5cb43534..a5742a20 100644
--- a/camlib.py
+++ b/camlib.py
@@ -8219,14 +8219,12 @@ def flatten_shapely_geometry(geometry):
     """
     flat_list = []
     try:
-        if isinstance(geometry, (MultiLineString, MultiPolygon, MultiPoint)):
-            for geo in geometry.geoms:
-                flat_list.append(geo)
-        else:
-            for geo_el in geometry:
-                flat_list += flatten_shapely_geometry(geo_el)
+        work_geo = geometry.geoms if isinstance(geometry, (MultiLineString, MultiPolygon, MultiPoint)) else geometry
+        for geo in work_geo:
+            flat_list += flatten_shapely_geometry(geo)
     except TypeError:
-        flat_list.append(geometry)
+        if geometry and not geometry.is_empty:
+            flat_list.append(geometry)
 
     return flat_list