No, what happened at the new place should have NEVER happened. No one should have left a 6 pound dog alone with a new dog, when that new dog is in an alterred state, off balance, re-homed, etc. That was human-fault all the way. A dog is ONLY a dog, and that little dog was not FAMILY to her.
Now, about the same-sex aggression, that will not go across other dogs, like on walks, or on people at all. It is pack/same-sex aggression. It is kind of like asking your wife if she minds you moving your high school sweetheart in until she finishes college.
Jenna, RN CGC & Babs, CD RA CGC HIC
Heidi, RA CGC
SG3 Odessa, SchH1, Kkl1, AD
Ninja, RN CGC & Milla, RN CGC
Joy, Star Puppy, RN CGC
Dolly CGC & Bear CGC