I am a step-mom to a 13 year old girl.
I'm so sorry you're going through this. My only advice would be to document, document, document everything that you can. If the divorce was done where you live and she hasn't changed anything (regardless of moving) any court cases would still be heard close to you, and that might discourage mom from doing anything. However, your dh needs to pay child support (although he might be able to get it reduced). It will look bad if he doesn't. When my ex and I lived in different states, we split costs for travel, and that was reasonable and approved by the court. I think that at some point, your dh needs to go to court, even if he has to represent himself. Are there any low-cost court services in your area?
I know all the rest must be pretty confusing. It sounds like your sd is lashing out, experimenting, pushing limits... but remember, with dh's ex as a role model, it isn't that surprising. TRY to stick with her and offer her support, but I think your dh is doing the right thing by continuing to bring up things that bother him(her myspace page, etc). It won't make him popular, but I bet that eventually she respects that.
Please feel free to vent. I wish I had better advice.
Welcome to the board.
I think you've posted here before about this situation, some months back.
<CENTER><A href="http://www.youngsurvival.org/"><IMG src="http://i2.photobucket.com/albums/y23/jennt1111/mindy2.jpg"></A>