Hi, I don't have any experience of adding a second dog after I had a dog since I brought home both my babies home at the same time. They are siblings and litter mates. You are doing the right thing by learning about her background, and doing a trial with her and Odin. In my experience I find a male and a female dog seem to get along better than two dogs of the same sex, but not always. Two Females can sometimes show jealousy towards each other, and two males can sometimes be aggressive. I hope you have a successful trial meeting with them and everything works out. Thank You for trying to rescue this baby girl and I hope she becomes part of your family soon. Please keep us updated on how it went.