They are probably busy allready. I can't keep my mollies from breeding. Just keep them healthy and let nature take it's course. Soon you won't know what to do with them all.
Try floating some hornwort or watersprite or anacharis in a large clump. Guppies/Mollies are topwater fish and the fry do best in floating plants for cover. TONS of plants is best for livebearers and will help keep your water leveled out.
