A pet store should have a device that might help, if you don't want to risk losing all of the babies. We had a small 'tank within a tank' sort of thing that you put the mom-to-be in. It hangs on to the edge of the tank, but has slots on the bottom. Ideally, when she delivers, the babies slip through the slots so she can't get to them. If you have more than one adult in the tank, you may have to put several in this smaller compartment. We usually had one tank as the 'maternity ward.' When a mommy Guppy was ready to deliver, we would move her to that tank, within the smaller compartment. After she delivered, she could go back into the big tank. The babies were moved in with the others after a few weeks, when they too big for the others to easily gobble in one bite.
It is quite interesting to watch, but I remember crying when I found out that the mommy would not deliver the babies again after eating them.
Good luck.