TinyPortal

Is there any way to share edit rights to an article, perhaps with a membergroup, like you can with blocks?

People can only edit their own articles, unless you give them permission to manage all articles.

If you want anything more, you'd have to code that option into TP.

Ok, the simplest workaround is probably to set up a fake user whose password is known to the collaborative group.   That's a known trick for group forum posts too :)