Summer visitation schedule dates no longer work with school

Erin, my custody & visitation order originated in Virginia ( I since have registered and domesticated it here in Charlotte). It states that ex has the kids for two 2 week periods in summer, the last of which is written as " from the second Saturday in august until 2 weeks afterward". EX lives in another County some 100 miles from Charlotte.
IN Virginia ( kids are now in elementary) school started on September 5th, so that schedule was ok, in Mecklenburg County school begins August 25th.
So based on the order, starting this year she would have the kids for 4 days AFTER school begins. Clearly this is not in the best interest of a 1st and 5th grader.

How and in what format do I best address this issue pro se to resolve it in the least involved fashion. My ex agrees ( at least for now) that the kids need to start school properly,but since past is prologue I want to have something written to enforce.

You will need to file a motion to modify custody, limited to the issue of summer visitation. If you and your ex agree to what the new terms will be you may enter a consent order and present it to the court without the need for a hearing.

If I file a motion to modify custody, am I understanding you correctly that I can “limit” it to just the issue of summer visitation ? If filed as such does that preclude Ex from trying to expand it to other area’s ( which after 3 custody battles which I won, I would like to avoid like the plague again)?

Yes. In fact that is the only issue that can be modified, as in my opinion, the change in the school calendar only affects that particular aspect of the order.