Do what I do...put newest kitty in a bathroom or bedroom with her food, water and litterbox while you feed the others away from her. Eventually, put a babygate in the doorway and feed them on opposite sides of the gate. It'll give them a pleasurable experience while protecting them both if one should get mad.

Oh yeah and one more thing...remember, "There IS no such thing as a family reunion in the feline family". I've got the scars to prove it!!