diff --git a/src/blackgui/views/aircraftmodelview.cpp b/src/blackgui/views/aircraftmodelview.cpp
index 03fbbfeb7..c1030bf83 100644
--- a/src/blackgui/views/aircraftmodelview.cpp
+++ b/src/blackgui/views/aircraftmodelview.cpp
@@ -143,6 +143,16 @@ namespace BlackGui
             return this->removeModelsWithModelString(models.getModelStrings(), sensitivity);
         }
 
+        int CAircraftModelView::replaceOrAddModelsWithString(const CAircraftModelList &models, Qt::CaseSensitivity sensitivity)
+        {
+            if (models.isEmpty()) { return 0; }
+            CAircraftModelList copy(this->container());
+            int c = copy.replaceOrAddModelsWithString(models, sensitivity);
+            if (c == 0) { return 0; }
+            this->updateContainerMaybeAsync(copy);
+            return c;
+        }
+
         void CAircraftModelView::setHighlightModelStrings(const QStringList &highlightModels)
         {
             this->derivedModel()->setHighlightModelStrings(highlightModels);
diff --git a/src/blackgui/views/aircraftmodelview.h b/src/blackgui/views/aircraftmodelview.h
index 22d04dfe5..b454759b2 100644
--- a/src/blackgui/views/aircraftmodelview.h
+++ b/src/blackgui/views/aircraftmodelview.h
@@ -64,6 +64,9 @@ namespace BlackGui
             //! Remove models with model strings
             int removeModelsWithModelString(const BlackMisc::Simulation::CAircraftModelList &models, Qt::CaseSensitivity sensitivity = Qt::CaseInsensitive);
 
+            //! Replace models with sme model string, otherwise add
+            int replaceOrAddModelsWithString(const BlackMisc::Simulation::CAircraftModelList &models, Qt::CaseSensitivity sensitivity  = Qt::CaseInsensitive);
+
             //! \copydoc BlackGui::Models::CAircraftModelListModel::setHighlightModelStrings(const QStringList &)
             void setHighlightModelStrings(const QStringList &highlightModels);
 
diff --git a/src/blackmisc/datastoreobjectlist.cpp b/src/blackmisc/datastoreobjectlist.cpp
index c3a1841b4..365703dc2 100644
--- a/src/blackmisc/datastoreobjectlist.cpp
+++ b/src/blackmisc/datastoreobjectlist.cpp
@@ -122,10 +122,10 @@ namespace BlackMisc
         CONTAINER newValues(this->container());
         const QList<KEYTYPE> keys(container.toDbKeyList());
         newValues.removeObjectsWithKeys(keys);
+        int removeSize = newValues.size(); // size after removing data
         newValues.push_back(container);
-        int delta = newValues.size() - this->container().size();
         this->container() = newValues;
-        return delta;
+        return newValues.size() - removeSize;
     }
 
     template <class OBJ, class CONTAINER, typename KEYTYPE>
diff --git a/src/blackmisc/simulation/aircraftmodellist.cpp b/src/blackmisc/simulation/aircraftmodellist.cpp
index 925bbbe7b..f05593b07 100644
--- a/src/blackmisc/simulation/aircraftmodellist.cpp
+++ b/src/blackmisc/simulation/aircraftmodellist.cpp
@@ -160,6 +160,23 @@ namespace BlackMisc
             return d;
         }
 
+        int CAircraftModelList::replaceOrAddModelsWithString(const CAircraftModelList &addOrReplaceList, Qt::CaseSensitivity sensitivity)
+        {
+            if (addOrReplaceList.isEmpty()) { return 0; }
+            if (this->isEmpty())
+            {
+                *this = addOrReplaceList;
+                return addOrReplaceList.size();
+            }
+            CAircraftModelList newModels(*this);
+            const QStringList keys(addOrReplaceList.getModelStrings(false));
+            newModels.removeModelsWithString(keys, sensitivity);
+            int removed = newModels.size();  // size after removing
+            newModels.push_back(addOrReplaceList);
+            *this = newModels;
+            return this->size() - removed;
+        }
+
         CAircraftModelList CAircraftModelList::findModelsStartingWith(const QString &modelString, Qt::CaseSensitivity sensitivity) const
         {
             return this->findBy([ = ](const CAircraftModel & model)
diff --git a/src/blackmisc/simulation/aircraftmodellist.h b/src/blackmisc/simulation/aircraftmodellist.h
index ec8406eb8..a23034bab 100644
--- a/src/blackmisc/simulation/aircraftmodellist.h
+++ b/src/blackmisc/simulation/aircraftmodellist.h
@@ -92,6 +92,10 @@ namespace BlackMisc
             //! \return number of elements removed
             int removeModelsWithString(const QStringList &modelStrings, Qt::CaseSensitivity sensitivity);
 
+            //! Replace or add based on model string
+            //! \return number of elements removed
+            int replaceOrAddModelsWithString(const CAircraftModelList &addOrReplaceList, Qt::CaseSensitivity sensitivity);
+
             //! Model strings
             QStringList getModelStrings(bool sort = true) const;