In a proceeding for a grant of custodial responsibility under this subchapter, the following 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 Commonwealth other than this chapter 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 Subchapter B (relating to agreement addressing custodial responsibility during deployment), unless the court finds that the agreement is contrary to the best interest of the child.