Aggression over toys

The last time that KD was adopted, she was returned for aggression over toys. Apparently the meet and greet with their dog had gone fine, but when they all got home, there was some problems with the dogs and toys. KD has shared space at the shelter in the outdoor runs with Hermes and with Valerie, so I know she can get along with other dogs. I had Lori's dog Emma over again the other day and she had some of her toys with her. KD loves stuffed squeaky toys and got ahold of Emma's little bone and I didn't notice it, but apparently Emma did, because I heard growling and squealing and I had to tell KD to get off of Emma (who is 1/6th her size) and send KD outside to break things up. It was then that I discovered she had the little stuffed toy. She ran around with it playing keep away until I grabbed a leash and she immediately came over to get a walk. When I took it out of her mouth, it was already torn open and the squeaker destroyed. In the past visits, Emma and she have gotten along fine. Emma even has a habit of taking KD's comforter spot and her bones. It seems there are some things that are the trigger and squeaky stuffed toys is on the list.