Amending stipulation agreement filed in VA

My husband & his ex-wife divorced in VA in 1990. They are both now residents of North Carolina. In the stipulation agreement he agreed to pay half of the children’s tuition to college. His financial situation has changed and we cannot afford to pay for the tuition. (Our children will need to take out student loans.) I know we need to get an attorney, but can you ammend a stipulation agreement through the NC courts or Va? thank you