(a) An order concerning visitation may be modified at any time if the best interests of the child would be served thereby in accordance with the standards set forth in § 728(a) of this title.
(b) An order entered by the Court by consent of all parties, an interim order or a written agreement between the parties concerning the legal custody of a child or such child’s residence may be modified at any time by the Court in accordance with the standards set forth in § 722 of this title.
(c) An order entered by the Court after a full hearing on the merits concerning the legal custody of a child or such child’s primary residence may be modified only as follows:
(1) If the application for modification is filed within 2 years after the Court’s most recent order concerning these matters, the Court shall not modify its prior order unless it finds, after a hearing, that continuing enforcement of the prior order may endanger the child’s physical health or significantly impair such child’s emotional development.
(2) If the application for modification is filed more than 2 years after the Court’s most recent order concerning these matters, the Court may modify its prior order after considering:
a. Whether any harm is likely to be caused to the child by a modification of its prior order, and, if so, whether that harm is likely to be outweighed by the advantages, if any, to the child of such a modification;
b. The compliance of each parent with prior orders of the Court concerning custody and visitation and compliance with each such parent’s duties and responsibilities under § 727 of this title including whether either parent has been subjected to sanctions by the Court under § 728(b) of this title since the prior order was entered; and
c. The factors set forth in § 722 of this title.