In a proceeding for a grant of custodial responsibility pursuant to sections 452.1224 to 452.1244, the following rules apply:
(1) A prior judicial order designating custodial responsibility in the event of deployment is binding on the court unless the circumstances meet the requirements of law of this state other than sections 452.1200 to 452.1258 for modifying a judicial order regarding custodial responsibility;
(2) The court shall enforce a prior written agreement between the parents for designating custodial responsibility in the event of deployment, including an agreement executed under sections 452.1214 to 452.1222, unless the court finds that the agreement is contrary to the best interest of the child.