Adding new Bangaii to existing one

[Carmen]

I had a problem with 2 wrasses much like what you are having. Original wrasse chased the ne one til he hid and could NEVER come out. I removed the initial wrasse and put him in the sump for 3 days to allow the newbie a chance to settle in and start eating. Then reintroduced the original and never had a problem after that.
You could try that but there are no guarantees I suppose that the move wouldn't totally stress the original Bangaai.
This way though it gives the "weaker" newbie a chance to establish his territory before she is added back. She will have likely forgotten her "territory" and be more likely to accept him.
Good Luck.