Can custodial parent take me off child support and then put me back on it again in the future?

I pay weekly court ordered child support for my 2 children. I have court ordered weekend visitation rights. My children's mother wants to move them to another state. She agrees to take me off child support and I pay her directly and to sign a legal document my lawyer will draft up stating she will never put me on child support again. Can she find a loop hole in taking my children without my consent? And can she, in the future still find a way to put me on child support even thought she signed the agreement?