If you want more babies, the best thing to do is to collect the wee ones when you first see them and put them in to their own tank. If they are too fast to catch with a small cup, try a net. Nets are best avoided with fry but molly fry are pretty big. If you don't want to set up another tank, you can put the babies in a breeder net. Otherwise, put in lots of cover like live floating plants and java moss so more babies might avoid being eaten. Molly fry are some of the biggest fry so usually some will survive when there are just mollies with them but your other fish may have more of a penchant for eating them.
My breeding page is at
http://www.fishpondinfo.com/breed.htm and has more on breeding fish and raising fry but is more geared towards egg-laid fry.