Before anything else it is important to have a medical workup to be sure there is no metabolic or other concern. If all is OK medically, this sort of behavior can be symptomatic of stress/tension and serves the purpose of tension reduction. There is little you can do from a behavior management perspective, since you generally do not view her while this is occurring. If she trult displays ADHD, treating this (i.e., with medication) could make a big difference. Has this been considered?
If you have not informed the prescribing doctor about this please do so.
We have tried a few medications, Right now shes on intuniv and strattera. She seems to be doing better with impulsiveness, she was very dangerous, and would do stuff without thinking. So thats better, but she still has to constantly do something. I put a camra in her room to see if i could see her doing this and thats when she was biting her purse. The whole time she was watching tv she was constantly moving her mouth and lips, biting purse, and putting fingers in mouth. Kinda look like her mouth needed to stay busy. I know its not the medication, bc she was doing this before medicene.