How to copy clip to another event as alias

I want to copy clips from Library A to Library B without actually copying/duplicating the source media. I want library B to reference the exact same source file as Library A.

I cannot see how to do this by dragging clips from one Library to the other from within FCPX, no matter what key combos I use. It either Copies it (fully duplicating the source file to the new Library directory) or Moves it.

However, if I go to the Finder and drag clips into FCPX while holding Option+Command, those clips stay put but are referenced in as many Libraries as I want.

The Finder option is not practical because I have hundreds of clips I need to "Copy".

Am I missing something?