Did you call and talk to the bride? Since she told you that your daughter was invited, perhaps it's a case of ummmm, how to say it nicely.....mom/mother in law, getting involved where she wasn't asked?
If bride says things have changed and she's not invited, then I'd not feel bad at all about bowing out. Sorry...but your acceptance was based on the WHOLE family be invited...that changed, so your acceptance has changed. If they think that's silly, then so be it. (Of course, my wise cracking mouth would probably ask then if it's silly, which one of the relatives is going to stay home from the wedding to babysit?).
You have to do what's right for YOUR family....and THAT family is you, husband and your child(ren). When you married you moved on to your own family and that family became your priority. Just like when your parents married, the priority became them and you kids. And so it will be when Lauren marries and choses not to attend family functions because it interferes with HER family priorities.
You'll never make everyone happy in life, so you have to decide who your priority for happiness is......some people choose everyone else, and are miserable....some people choose themselves and make everyone miserable...and the wise ones choose to make their nearest and dearest happy and at the same time get their own happiness!
It's not easy the first time, but it's easier after that.