Ya but thats only 3 fish in that 30g so really we can fit 30" of fish..so let's throw another one in!!
OP we like to poke here so dont take it personally. Lots of people have tangs in smaller tanks and eventually with all good intentions go to a bigger tank or in the unfortunate cases die due to aggression or worse.
You have the tangs so getting them happy is the most important. Before taking back the PB, definitely move some rocks around and make new houses for everyone and see if that works. With no established Hole/home they might rework where their territory is.
Good luck with this and I hope they play nice!

