United dwarf army

So a friend of mine wants to join AoS yay!

I used to have the Battle for Skullpass box back in the day, and we used to battle against eachother (with our own made up rules because we were too young to understand it yet). So I'm feeling very nostalgic.

I currently collect Gitz and he wants to collect dwarfs, however he doesnt like that homogenous style of the dwarf armies. I googled if you can mix Order fractions together and there used to be a 'mixed' dwarf army of renown, however that appears to be an older edition if AoS. Does something like this still exist? Or can he just use that older AoR?