It's his weekend, his problem. I can't believe how little time he spends with Marc. Well, actually, I can. I just think it's positively shameful.
Just tell him you need more notice to switch weekends.
While he's right that Marc can take care of himself for small periods of time (and I'm very glad of that because that takes some stress off you!) that's still not cool of him.
Michelle - Proud DR Rockette S: 28JUL07, D'd: 29OCT09 http://tinyurl.com/27j9qo2