Give them lots of places to hide and make sure they can't get sucked into your filter. They will end up like when Nemo couldn't swim out the tube on the Emperor 400.
if you want the guppy fry to survive then i suggest buying a few tufts (or bunches) of java moss and they should hide in it also try adding some marble sized/large stones in the corner with the moss and they will hide in the moss and under or in cracks between the stones,
I have many guppies to feed my bigger fishes and every time i have baby guppies i put them in an other aquarium : in this manner they get enough food...