If you want to keep them, and grow them fast, here are some tips:
-You should have some sort of floating plants like hornwort/anacharis and a cover on your intake for your filter so they don't get sucked in. You can use a piece of mesh fishnet or filter floss or even a nylon stocking. Just tie it on somehow. It may reduce your filter flow though depending on the type of filter so clean the intake often.
-Feed them powdered food at least 3 times a day. Just squish whatever food you already feed the other fish into a fine grit so they can eat it ok. You can also buy special fry food and baby brine shrimps. They should have a lot of algae in their diets. You may want to have one rock or back wall full of algae they can graze, the adults will eat it too.
-Keep the temperature around 80 and they grow faster and are more active. Mollies prefer higher temps.
- You should have a plan in case you get too many babies. Remember the mamas can drop over 50 fry each month. You can sell the good looking ones and use any deformed/other culls as feeders, letting nature sort it out usually resorts in stronger babies surviving. Also if you want to, you can set up a barebones cycled tank with a sponge filter for all of the fry! It should be at least 10 or 20 gallons.
-Last one is obvious but keep up on water changes! Mollies are sensitive compared to other livebearers.
I kept mollies and sold the babies for a long time.