Oh gosh, loaded question! lol
Dynamics change, I can tell you with certainty that Toffee was way less scared, anxious or frustrated with Misty (ex roomies dog) around, so he was able to relax much faster than ever before. He took his queues from her, and she was such a sweet, calm dog, too
As you know personally, I have always speculated that Ellie although special, underneath her tough cookie facade is more scared and frustrated. When she is made to supress things, and only offer 'good' behaviour other issues are showing up it in other ways.
However, you know her just so much better! I know we always kinda disagreed about some of your trainer's ideas, lol, whom you and Ellie adore. So it may be time to ask her about this and no need to worry about what I may be thinking, lol.
Ellie sure is a wild but insecure and scared child, but I totally adore her and your dedication to her!! You guys are doing so many wonderful things, don't let that discourage ya... she seems to love Ginger and it sounds like a great friendship! ... as long as you guys control the resources like couch, toys, you guys, food, etc... as she seems to be resource guarding when she is giving Ginger a beating, lol