Hate to rain on your parade, Andrea, but bedwetting is not a disciplinary problem. I know I was one and I still remember my grandmother rubbing my nose in it (literally), though I'm not suggesting you would even consider such action.
It is a physical or emotional issue - if she's only started this since the babies' birth, then she may be feeling a teensy bit abandoned. Remember, emotions are not logical - don't think you've been a bad mommy bc she's having this little problem.
The other possibillity is physical - her bladder is too tiny to make it through the night and you may need to try cutting back on fluids, especially anything with caffeine, in the evenings.
In the mean time, until you both have this problem licked, it might be easier on the two of you to try overnight pull ups.
I also had to deal with this issue with my son, he slept so deeply he just couldn't wake up. He finally grew out of it. The only cure is patience.