Maintain Opening / SEO for Copy

[thesleepofreason]

When copying an element that is involved in an opening or SEO it should be possible to maintain that for the copy . For example - when copying a slab/roof/wall in order to add a layer to the modelled building part we now have to add all copies to existing openings which is very inefficient. 

[hmartell]

This would be great when copy objects that cut other objects. For example, when copying a slab that cuts a mesh, that copy should also cut the mesh, etc.

[graber]

and it would be great, if the SEO was kept, when splitting an object, on both parts, too.