Damsels are VERY aggressive, they will probably attack the new fish, my opinon, ask the lfs if they want it for store credit or not, damsels, except chromises will often nip their tankmates
just my opinon, if you want to keep them its alright, just beware that the damsels MIGHT attack the new fish and sometimes they will get along after awhile and sometimes they dont.
You can try this technique, turn off the lights in your tank and move around the rocks in different areas, and then introduce your new fish (after aqqumilated) and then turn on the light, i only heard about this and never tried it out but its worth a try
