It's certainly a hard time for her. Between the time of Elizabeth's death and Henry's birth Mary was Eleanor's only living child, so she has a special bond with her, one that makes marrying her off terribly hard. As for James, well he might, hopefully he'll recognize that he can't live the same life he lived as a bachelor. Mary most likely will be more patient, she's received some good advice from her mother before the wedding after all, and she saw that (directly) fighting over affairs had mixed results at best for her mother...Poor Eleanor. Hopefully James learns discretion with his affairs and Mary takes after her mother’s more prudent qualities.
She'll need the luck for sure, but she's also partially witnessed the early struggles of her mother's marriage to her father, so she knows that discretion is key.Good luck to Mary, perhaps she can manage James like Eleanor came to manage Henry.
At least your daughter is in Scotland Eleanor and not as far away as Poland or Hungary, you can still write quickly and of course your Progress should be able to get this far north occasionally for a meet.