I don’t have enough information to determine if your daughter is experiencing “Stockholm Syndrome.” You did give me enough information to cause me great concern.
Please don’t rely on the Internet to figure out how to help. While you are researching and trying to sort out what is said on Internet sites, valuable time is passing. Your daughter is in distress now. When a 9 year old starts having “accidents,” she is asking for help.
Please talk to your doctor, lawyer or a school counselor about your concerns. Ask for a referral to a therapist who specializes in children and trauma. Take your daughter for an evaluation. The therapist will be able to determine what is going on with your little girl and will offer you guidance for how to help her — and help yourself.
I wish you well.