The pair of guppies had been breeding like crazy and the 3 to start was now 40!
Am I missing something from what you posted? You want the breeding frenzy to discontinue because of the proliferation of guppy breeding? You should have some idea of the sex of the original pair since they have already mated and spawned. That is the pair you can concentrate on for now. It won't be long until you can sex the others as well.