I got a really cool idea for subscriptions.
Just hang around and read!!!
Ok so say your doing s collab with someone, on YOUR account you have a sub with the person your collab with does not, I feel you should be able to make a collab account and they should have a link button and you type your username and password in to that link and then you have the sub on that collab or wherever account as well.
Doesn't make scence? Ask questions!