Just went through this with my mom filing for grandparent rights and saying I was keeping the kids from her because I had to move out of state, when she got them for her two weeks in the summer she refused to let them come home, I would call them and she would not let me talk to them, I could hear them crying and asking for me, finally my ex father-in law (the kids' dads dad) called and asked to spend the day with the kids, and I called the police to let them know what was going on and she let him take the kids for the day, and he drove them home... then tried to call the cops saying he kidnapped them, that is when they told her she was lucky he got to bring them home and she would have charges filed if she tried this again.... it is scary and truly the only thing you can do is stay on top of things, document every thing, make copies of messages on the computer, sign and date all agreements, time of pickup/drop off that way you and he are both covered... and keep busy as you can doing things until you get the call or knock on the door that they are home! Good luck and praying for a fast return!