Is it possible to share files between iCloud Music Libraries? Previously, my wife and I shared a single iTunes store account and had iTunes match. If I added music to my library from outside iTunes, she could see it in her library and download it to her phone.

Now we have switched to Family Sharing, an Apple Music family plan, and iCloud Music Library (since our collection(s) are far larger than could fit on our phones). She signs into Apple Music with her Apple ID, I sign in with mine, and everything is great. Our customizations in Apple Music don't affect one another.  We still use the shared iTunes account on our Apple TV for kind of joint music access.

From time to time, though, either she or I acquires music from outside the iTunes store, for example directly from an artist or at bandcamp.com or what have you. Does anybody know an easy way for us to share new music additions with one another or the original joint account? The only way I have found so far is for me to AirDrop or Dropbox a folder of music files from my Mac to hers… but that requires tracking what we've downloaded, what we've shared, and for us to be in "let's do computer busywork together" mode at the same time. Even worse, since neither of us is signed into that original iTunes account, to update that library I have to sign out of iTunes on my Mac, sign in with the joint account, and add the music, then switch back, and then I have to go through the whole process of iTunes tagging my music for iCloud Music Library and waiting a long time to sync the library.
I understand the issue and simply, the answer is no.

Apple's Family Sharing is limited to iTunes purchases (music, movies, TV, books). What it does not provide is access to the main account's full iCloud Music Library. While the main account can add, access, and delete non-iTunes media to the iCloud Music Library, it cannot share that content, even with those in Family Sharing. I think it stinks and cripples the value this service. 

I can only imagine this is Apple (and thusly, music industry) trying to thwart major music peer-sharing in constantly shared "Family" libraries.