A standing child custody order may be modified if one parent demonstrates that a material change of circumstances occurred. (divorcesource.com)
Essentially, a party wishing to modify child custody must show that a significant change of circumstances has happened. (flanderslawfirm.com)
The move or removal will result in a substantial change of circumstances since the entry of the last order affecting legal custody or the last order substantially affecting physical placement. (divorcesource.com)