In a proceeding for a grant of custodial responsibility pursuant to this Part, the following shall apply:
(1) A prior judicial order designating custodial responsibility of a child in the event of deployment is binding on the court unless the circumstances require modifying a judicial order regarding custodial responsibility.
(2) The court shall enforce a prior written agreement between the parents for designating custodial responsibility of a child in the event of deployment, including a prior written agreement executed under Part 2 of this Article, unless the court finds the agreement contrary to the best interest of the child.