Copying nested families with Dynamo

Yes it is possible, but you will need to open the family or edit it if in a project, the get the nested family you want and copy it to where it needs to go. A python solution would be the cleanest, but check out Orchid package as it will have many nodes you will need. Also Genius Loci package I believe will help.

Check this post I had a while back, it has a lot of things that can help you.