So, we had major drama at the beginning of the summer:
1. My older step-son (DH's son from his 1st marriage) got married the 3rd weekend in June, which is a bit later than 13-year-old DSS's mom tends to start her summer visit.
2. We took advantage of a good deal and got plane tix for DSS to fly back from Mom's for the wedding and back out to her, afterward. DH told her about these tickets - and the wedding - 6 months in advance.
3. She cancelled the tickets. DH re-reserved them. She cancelled them again.
4. DH said, "Then just start your summer visit after the wedding!" After all, upon closer examination we realized:
--- Each of the last 4 years, Mom has elected to start her summer parenting time on Friday, either the 2nd or 3rd weekend in June. So keeping DSS with us through that 3rd weekend and flying him out to her Monday deviated from her normal schedule by as few as a couple of days.
--- When they filed for divorce, the NCP got to unilaterally choose the summer dates. They continued that practice, on auto-pilot, even after Mom moved to California and DH got custody. But it turns out the "unilateral" part is only for parents who live near each other. "When distance is a major factor", the summer visit is to be scheduled around the kid's activities and commitments.
5. True to form, Mom bought tickets for DSS that started his summer visit in the very beginning of June, right before his birthday, such that he wouldn't be here for the wedding.
6. Since DSS was 8, Mom has neither chosen to have him on his birthday, nor come here to visit him then. But this year - when it could keep DSS away from a major family event with us - it became her top priority. She promised a big party in CA, with friends traveling from out of town to be there (her friends, not DSS's...but still. It sure sounded rotten to ruin such an event, by refusing to send DSS until after the wedding.)
7. DH asked Mom to come and spend DSS's birthday with him here. We offered to let her have him the whole day and to celebrate with him a different day, ourselves. DH encouraged her to consider how DSS would feel, if he missed his brother's wedding. Well, she thought DH should be compassionate toward DSS and consider how he has suffered through so many recent birthdays "away from his family". She was resolute about only spending DSS's birthday with him on her turf. How can one possibly negotiate with a person like her?
It was a really hard call, but in the end we did not send him on the outbound flight Mom bought. We bought him a ticket to fly out there after the wedding, then welcomed her to change the return flight she'd purchased, so he could spend the full 7 weeks with her. Poor DSS got to hear from not only Mom, but her parents and her best friend about how his absence ruined "the entire month of June" for them, but that of course it wasn't his fault, they were sure he felt just as upset as they did.
After all that, I was bracing myself for how DSS would be, when he got home. Mom did change his return flight, but still sent him back a full week earlier than she had to!
Naturally, she chose a flight where DSS had to change planes alone - on an airline that doesn't offer Unaccompanied Minor escorts - something DH has been fighting to keep her from doing, for years. Indeed, this first time DSS changed planes alone, his connecting flight was cancelled and he was stranded for several hours in a city hundreds of miles from anyone he knew.
But he's home now, and seems fine. He's very pleasant, glad to be back and eager for school to start. What a relief!