I think it would be beneficial for you to identify a local professional who could give you some suggestions regarding how to improve compliance and provide some strategies for addressing the other behavior problems that you are experiencing. The website of the behavior analysis certification board has a listing of certified behavior analysts by state at this link: http://www.bacb.com/consum_frame.html.
I would want to be sure that you have access to a professional who could recommend a wide range of safe and appropriate behavior management strategies. It will be important to address this issues now. She will be much more difficult to manage when she gets bigger and behavior problems will descrease her opportunities for learning.
Question is, where did she learn it? My son learened to cuss and then unlearned it, while dad was not cussing, then started all over once Dad slipped into cussing. He started back full throttle the very second he heard Dad cuss.
Locking in a bedroom is a bad idea. Being consistent in both households is a good idea. Timeout can be implemented, but if she never "stayed" in timeout - expect her to escalate behavior for about 2 weeks. Still, be consistent and keep returning her to time-out, do not talk to her.
For me, the most succesful strategy with cussing was to correct him (we do not say these words) and do not show too much emotional reaction. Then it goes away (for 2 weeks it will be getting worse, then better).
Problem with time-out use in children with ASD is that many do not care about it and actually enjoy it.
It does not matter whether the behavior is
She will get it.
sorry, appropriate way to discipline