Hang in there, it'll get better. I've been doing this for many years and have encountered similar situations. She could be overwhelmed by the whole transition or she could just be checking you out to see how far she can push you. Though it may not be a popular philosophy by today's standards, but I believe in being resolute with boundaries and rules....in other words, I'm strict. There is no bending and I've found, even with difficult children, it always works itself out. Sometimes you have to change your approach with different children, but in the end, if the rules are strongly enforced, she will come around. I often don't take the kids out to different locations until a new one who's having trouble adjusting to the new setting has settled in. Then I add outings in slowly....to test the waters so to speak. And when she responds with appropriate behaviours, bring out the ticker tape and brass bands.....positive reinforcement all the way

I also talk to the parents about the behaviour and explain my strategy for that child with them. Most times, parents are willing to reinforce this at home. Consistency between environments certainly helps loads.

Good luck!