1. It should be 'revised' from jurisdiction Court and not personally between parties.
2. After 90 days of knowledge of Decree in Divorce proceedings parties are at liberty to get re-married.
BTW, if relations between ex-spouses are still cordial the ‘change in circumstances’ r/w mutually agreed revised terms and conditions between parties for visitation of minor with non-custodial parent can sail smooth and if there are objections from natural mother then same can still be sorted out harmoniously. Normally what I have seen is that if parties mutually agree before approaching for revision then more time during visitation once or twice a year gets allowed as revised understanding of parties over their current agreement. See where you stand today with your ex wife reading down this large summing up para and then act accordingly! BTW, during discussion with ex don't hint on re-marriage instead concentrate on better quality of living for minor of parties in USA as one of the reason for approaching for 'revision of previous MCD terms'.
[Also try to get hold of same Advocate who effected MCD of parties as he may know the finer sail trough facts of parties to then have achieved MCD of parties.]