Sundae, stop by on your way back from Kenya and I'll see what we can do.
Squid -- absolutely true; there's nothing my parents wouldn't have done for our kids. But of course, grandparents aren't obligated to do anything legally and, some may say, even ethically. There are a lot of parents who think when the kid's 18 they're done in every way, including caring for grandkids.
The problem with asking your ex's mother for help is that it means she's always going to be nosing around in your life, if she's inclined to do so. But good moms (and I did say she was one, mostly) will be able to deal with that if it's important to the kids' well being.
It must have been very, very hard to ask.