I wouldn't take a chance on introducing them to an existing tank. I had a bad aiptasia outbreak a few months ago. After trying to physically remove them then using Joe's Juice, I ended up buying a few Berghia nudi's and they mowed through them within a couple of weeks. It was actually pretty amazing how well they worked. One day the aiptasia was there, and all of a sudden it was all gone. I never once saw the Berghias, but they most definitely did the job. If you're looking for a source to purchase PM me, the company I worked with was excellent.
I would suggest moving the corals (and any other rocks/animals) with aiptasia to a q-tank and treat them there. As an added bonus, once the Berghias clear the aiptasia you should be able to round them up and sell/trade/give them to another aquarist.