BBM: Well, he couldn't very well keep his promise to take him to his friend's after he got back, when Dylan wasn't there when he got back, could he? That's not a lie just because it didn't happen. You make it sound like he had no intention of taking him at all, and we don't know that. If Dylan wanted to go to his friend's house so badly, why didn't he get out of bed that morning when his dad tried to wake him? Apparently, it wasn't as big a deal to him as people are making it out to be.
I assume since these visits were court-ordered, that they had an option, either going for Thanksgiving, or Christmas. What kid wouldn't prefer spending Christmas at the home he lived in most of the time, with his mother and brother, rather than with his dad by himself? And it's possible that he really wasn't given a choice, that this schedule was worked out by the judge, or between the lawyers during the custody hearing. It's fairly common to alternate holidays, one year Christmas with Mom, the next year with Dad.
Sometimes the parents work out the schedule themselves, but I doubt if that happened here, since they don't communicate with each other.
Plus, I was under the impression that the Thanksgiving plans were not solid yet, so where are we getting that Mark was buying stuff to make dinner? Perhaps he was asked to bring a dish of something, or a couple pies to contribute to the dinner at his brother's house.
I may be missing some details that have just come to light, but I'm seeing an awful lot of assumptions in these posts, (not just yours) and would just like to get some things clear in my mind.