This is a tough one. I completely understand where you are comming from. Having said that, it is two wks before your DD and it is his sisters wedding. I think I would either be going with him, or allowing him to go with a strict timeline of when he has to be back and beiing contactable at all times.

But that is just me. It really is a hard position for both of you to be in. from your veiw, you want him there JIC. From his veiw the likihood of him needing to be there at that point in time is very slim, and he will resent you for it if you don't 'let' him go and the baby doesn't make an appearance - which statistically speaking it probably won't).