I have kept multiple dwarfs together several times over the years. The acclimation box is your friend. Leave the flame in it for up to two weeks until you can tell both fish have given up on getting at each other. If its possible to move a rock or two around in the tank, that is always beneficial. When you introduce the flame, go a day without lights... it wont hurt coral or anything, this will disorient them some. Then when you bring the lights back on the next day they should be fooled. You will always have some minor squabbling at first, but remember, they have to establish their territories. This is my personal experience. Best of luck!
BTW Pygmy Angel Formula is the food you are after, feed it often.