Don't call your lawyer yet. Shoot her a delicate email simply stating you would have liked to have had them this weekend instead of them being at her moms. Remind her (nicely) of the right of first refusal issue. Don't start fights yet. Just state your case and leave it at that.
One more thing, your a parent right???? I don't give a crap what she is calling you about, call her back because one of these days it will bite you in the ass if she cant get ahold of you or you dont respond and it is regarding a serious kid issue. You call her back, if its not about the kids, then say adios.
Your primary responsibility is as a dad so just return the stupid calls.
