I personally would not be including the formally known part in combination of the current name. That can be a very sensitive part of the process and, many when they drop their name are looking to just leave that part of their life behind, and attributing to it would be a link to it.

I agree with the other person, if I had contact with the artist, I would ask, if not I would default to the name that was present when the art was made. but I also would not link to a website as the new website would almost certainly be the current name.

You could also look at the current art to see if they have the sources under the old or new name as well if it was re-uploaded, if so then its probably safe to use the current name.

That’s pretty tough.