Successful reproduction of large-ish snail species like Margaritas (which IME are usually some other genus like Tegula sold under the wrong name) and Turbos in the aquarium is quite rare since they all have to go through a planktonic larval stage that is quite fragile. Although it's not impossible that you had survivors that turned into little snails, it's more likely that you have a small species of some other snail that has showed up, such as Colonistas. Either way though, there's not a lot you can do care-wise beyond keeping your water quality high and avoiding adding other herbivores that would compete for food. To cultivate a snail population, it's also a good idea to avoid cleaning the tank walls for a while if that's something you normally do. The reason for that is both to avoid accidentally damaging small snails and to allow more food-growing surfaces for the snails to forage on to minimize starvation risk.