Update on anticipated problem
BM decided that since she wasn't getting her way, she should start harassing DH's lawyer, (that represented him many years ago during the divorce). DH and his lawyer talked and the conversation went something along the lines of:
Lawyer: You have precedent because she followed "your" interpretation every year since the parenting agreement. If it went in front of a judge, she would look foolish and I told her this. She doesn't care and it still pressing the matter. In situations like this where one party is arguing for a point so strongly without regard to precedent, I try to find the motivation behind changing something already in existence and working flawlessly. It seems she just found a loophole and wants to take advantage. Do you realize she is arguing for less time with the kids?
DH: No I didn't.
Lawyer: Her way, (if the school has 3 or less snow days added at the end of the regular calendar year), every summer in the future she loses 8-12 days. In fact, I looked over all her past complaints about parenting time and every time she has a problem with the parenting schedule, she argues for an interpretation that gives her fewer days.
DH: Well if she thinks she is winning by fighting to have the kids LESS time, then she is stupider than I thought. Give it to her and we just won't be able to plan our summer vacations until we know the bad weather has stopped for the winter.
So, this summer she will lose 8 days she could have had them and will be giving DH two weekends in a row at the beginning of the summer and end of the summer. Next summer she will lose 12 days and double weekends again. This is how she wants to interpret the parenting agreement.
I could not wrap my head around her wanting less time with her kids, but in looking back she argued this before the parenting agreement was in place. She is phasing them out now that they are teenagers. They just got cars and are driving themselves now. I think they are going to spend even less time with BM now if she is giving off this vibe of "less time here, more time with your dad"