Perhaps you can achieve the same result by editing the layers individually and after finishing editing on those layers all you need to do is 'merge visible layers', making them into a single layer.
First, make visible only the layers you want to merge.
Right-click on a layer in the layer dialog window and in the pop-up that appears select: Merge - Visible - Layers ...
First, make visible only the layers you want to merge.
Right-click on a layer in the layer dialog window and in the pop-up that appears select: Merge - Visible - Layers ...