Hi. I'll share my experience with tangs first, and then ask a question.
My first tank had a Hippo tang and a Yellow tang. I had no idea that tangs could be aggressive. Then I added a blue powder to them and didn't see any aggression.
When I started the second tank, I was told about their aggression at LFS, and was advised to start Blue Powder first because of his tendency to stress and illness as a result.
A couple of months later, Yellow and Sailfin were added. I thought he would kill them, because he immediately attacked them. In the morning, all three swam like friends, but it was clear that they pronounced it as a dominant.
Moving to another city and another tank was a heavy price for me. Apart from sailfin, no one survived (it's a long story).
A Purple tang was added to the new tank. At first, there was some aggression, but it passed quickly enough. Next was Foxface, but he was able to fight off both thangs, so they still don't like him, but they don't bully him too much.
Now the question.
I want to add more surgeons. I have a list of those I like. Yellow and Achilles I am not considering yet because they are expensive. Of what I am considering
Blue Powder
Naso
Sohal
Clown
Should I add two thangs at the same time?
What size?
I don't have QT, so I think it is better to buy them not in LFS.
Thanks