When you type git tag you'll get list of all tags in your repository. Remote tags also show here, and I don't know if they may conflict (didn't check that), and how to check what tags were imported to your repository.

But what I checked is that when you add remote and it fetches from other project, you see what tags are imported. Then you can merge with that tag, for example:

git merge -s ours --no-commit v0.1.2 # instead of: Bproject/master (2)
git read-tree --prefix=dir-B/ -u v0.1.2 # instead of: Bproject/master (3)

and it should work.

Hope it helps a little, but I'm not as advanced with git as I would like :-)