Unable to combine multiple pets in photos

I adopted a new kitten a few weeks ago, and ended up with 4 albums for him. One I think is a person, an actual contact. One I was able to combine with one of the others, and then another album showed up for him with a different picture. So I am back to 4 albums for him.

I tried adding the main album and deleting him from the others and that seems to work on some images but not others.

If I select two or more albums and try to merge it is greyed out. If I try and drag them into one another the other album moves.

Anyone found a solution for this situation?

Kitten tax:

The first time I met him.

After spending about 20 minutes taming him.

Big stretch.