If this is your wether that was gettting antsy, I would remove him before introducing the new girls, just takes away another chance of fighting.
If your current girl is disbudded then it may be asking for trouble introducing her to horned new goats though.... people do keep horned with disbudded goats, but only when they have grown up together, never wear collars and have enough room to keep separate.
I would house all the goats together in one shed, but with different pens, initially with a gap between the pens , then just a hurdle bewteen them, then sharing a hayrack. I wouldn't let them outside for at least a week, just so they get used to the idea of sharing the space, and for the new girls to get the idea of where "home" is.
It really depends on the character of the individual goats, some will b eok with newcomers sooner than others.