diff --git a/src/App/ExtensionContainer.cpp b/src/App/ExtensionContainer.cpp
index b3688d51ba..be52ac6922 100644
--- a/src/App/ExtensionContainer.cpp
+++ b/src/App/ExtensionContainer.cpp
@@ -94,7 +94,7 @@ bool ExtensionContainer::hasExtension(const std::string& name) const {
 }
 
 
-Extension* ExtensionContainer::getExtension(Base::Type t) {
+Extension* ExtensionContainer::getExtension(Base::Type t) const {
    
     auto result = _extensions.find(t);
     if(result == _extensions.end()) {
@@ -115,7 +115,7 @@ bool ExtensionContainer::hasExtensions() const {
     return !_extensions.empty();
 }
 
-Extension* ExtensionContainer::getExtension(const std::string& name) {
+Extension* ExtensionContainer::getExtension(const std::string& name) const {
 
     //and for types derived from it, as they can be cast to the extension
     for(auto entry : _extensions) {            
diff --git a/src/App/ExtensionContainer.h b/src/App/ExtensionContainer.h
index 1108a75dfb..511d70e6ed 100644
--- a/src/App/ExtensionContainer.h
+++ b/src/App/ExtensionContainer.h
@@ -127,12 +127,12 @@ public:
     bool hasExtension(Base::Type) const; //returns first of type (or derived from) and throws otherwise
     bool hasExtension(const std::string& name) const; //this version does not check derived classes
     bool hasExtensions() const;
-    App::Extension* getExtension(Base::Type);  //returns first of type (or derived from) and throws otherwise
-    App::Extension* getExtension(const std::string& name); //this version does not check derived classes
+    App::Extension* getExtension(Base::Type) const; 
+    App::Extension* getExtension(const std::string& name) const; //this version does not check derived classes
     
     //returns first of type (or derived from) and throws otherwise
     template<typename ExtensionT>
-    ExtensionT* getExtensionByType() {
+    ExtensionT* getExtensionByType() const {
         return dynamic_cast<ExtensionT*>(getExtension(ExtensionT::getExtensionClassTypeId()));
     };
     
diff --git a/src/App/GeoFeatureGroupExtension.cpp b/src/App/GeoFeatureGroupExtension.cpp
index 71dfe2d9cc..d10391559f 100644
--- a/src/App/GeoFeatureGroupExtension.cpp
+++ b/src/App/GeoFeatureGroupExtension.cpp
@@ -92,7 +92,7 @@ std::vector<App::DocumentObject*> GeoFeatureGroupExtension::getGeoSubObjects ()
         std::set<App::DocumentObject*> nextSearchSet;
         for ( auto obj: curSearchSet) {
             if ( isNonGeoGroup (obj) ) {
-                const App::DocumentObjectGroup *grp = static_cast<const App::DocumentObjectGroup *> (obj);
+                auto *grp = obj->getExtensionByType<App::GroupExtension>();
                 // Check if we havent already processed the element may happen in case of nontree structure
                 // Note: if the condition is false this generally indicates malformed structure
                 if ( processedGroups.find (grp) == processedGroups.end() ) {
@@ -127,7 +127,7 @@ bool GeoFeatureGroupExtension::geoHasObject (const DocumentObject* obj) const {
         std::set<const App::DocumentObject*> nextSearchSet;
         for ( auto obj: curSearchSet) {
             if ( isNonGeoGroup (obj) ) {
-                const App::DocumentObjectGroup *grp = static_cast<const App::DocumentObjectGroup *> (obj);
+                auto *grp = obj->getExtensionByType<App::GroupExtension>();
                 if ( processedGroups.find (grp) == processedGroups.end() ) {
                     processedGroups.insert ( grp );
                     const auto & objs = grp->Group.getValues();
@@ -148,11 +148,11 @@ DocumentObject* GeoFeatureGroupExtension::getGroupOfObject(const DocumentObject*
         GeoFeatureGroupExtension* grp = (*it)->getExtensionByType<GeoFeatureGroupExtension>();
         if ( indirect ) {
             if (grp->geoHasObject(obj)) {
-                return dynamic_cast<App::DocumentObject*>(grp);
+                return grp->getExtendedObject();
             }
         } else {
             if (grp->hasObject(obj)) {
-                return dynamic_cast<App::DocumentObject*>(grp);
+                return grp->getExtendedObject();
             }
         }
     }
diff --git a/src/App/GeoFeatureGroupExtension.h b/src/App/GeoFeatureGroupExtension.h
index 901b34bcfd..c6fe4a9f9f 100644
--- a/src/App/GeoFeatureGroupExtension.h
+++ b/src/App/GeoFeatureGroupExtension.h
@@ -73,7 +73,7 @@ public:
 
     /// Returns true if the given DocumentObject is DocumentObjectGroup but not GeoFeatureGroup
     static bool isNonGeoGroup(const DocumentObject* obj) {
-        return obj->hasExtension(GroupExtension::getExtensionClassTypeId()) & 
+        return obj->hasExtension(GroupExtension::getExtensionClassTypeId()) && 
                !obj->hasExtension(GeoFeatureGroupExtension::getExtensionClassTypeId());
     }
 };
diff --git a/src/Gui/ViewProviderGeoFeatureGroupExtension.cpp b/src/Gui/ViewProviderGeoFeatureGroupExtension.cpp
index d8593d4ad7..d9221c3da1 100644
--- a/src/Gui/ViewProviderGeoFeatureGroupExtension.cpp
+++ b/src/Gui/ViewProviderGeoFeatureGroupExtension.cpp
@@ -99,7 +99,12 @@ std::vector< App::DocumentObject* > ViewProviderGeoFeatureGroupExtension::getLin
     if(!obj)
         return std::vector< App::DocumentObject* >();
 
-    //we get all linked objects, and that recursively
+    //if the object is a geofeaturegroup than all dependencies belong to that CS, we are not allowed 
+    //to grap them
+    if(obj->hasExtension(App::GeoFeatureGroupExtension::getExtensionClassTypeId()))
+        return std::vector< App::DocumentObject* >();
+    
+    //we get all linked objects
     std::vector< App::DocumentObject* > result;
     std::vector<App::Property*> list;
     obj->getPropertyList(list);
@@ -123,7 +128,7 @@ std::vector< App::DocumentObject* > ViewProviderGeoFeatureGroupExtension::getLin
 
     //collect all dependencies of those objects
     std::vector< App::DocumentObject* > links;
-    for(App::DocumentObject *obj : result) {
+    for(App::DocumentObject *obj : result) { 
         auto vec = getLinkedObjects(obj);
         links.insert(links.end(), vec.begin(), vec.end());
     }