Originally Posted by hyperskeptic
Vix and the girls will have to come back home a week before I do, so the girls can start school.
Is this part set in stone? As a teacher, I can tell you that students miss school for a week or more due to family travels all the time. The girls' school likely has some sort of Independent Study they can do to make up the absences, if you're concerned about that, and even if they don't have a standard policy in place I'll bet something can be worked out since they'll be abroad.
If you CAN'T come back early and she WON'T leave later, then this is the compromise I'd make- have the girls miss the first week of school (a little disappointing for them, maybe, but it shouldn't be a huge deal) and come back with you. This could also possibly cut costs on plane tickets, if your wife stays as well and travels from the UK to Germany to see Doc and attend the event rather than going home and going BACK to Europe just days later.