Custody Modification

My divorce dissolution includes an unusual custody agreement. We have joint physical/legal custody and my son has been with me from 2nd grade through 5th (this school year). Our agreement states that my son will live with his father in Indiana form 6th grade through 8th. Of course many things have changed, including the birth of my son’s half-brother who is now 4 years old, my remarriage, and my job. My son was doing poorly in school until he settled in with us and would be going to the magnet middle school that I teach at should he remain here. My ex agreed months ago to allowing our son to stay through 8th grade but recently changed his mind. Now I have 6 months before he is to move back to Indiana. I feel that I am the more stable provider as my husband has not had stable employment and has not been able to pay child support for 14 months.

Can I modify our custody agreement here in NC? I have searched and searched and have not found any definitive answers and it is very frustrating not knowing if I should be contacting an attorney up in Indiana or down here.

Is this an order from Indiana?

If the original order was entered in Indiana jurisdiction remains in that state and the modification should take place there.