First, the hot glue won't hurt them, but what material are you using for netting? Are you looking to contain the fry in the breeer net? If so how long do you plan to hold them there? I'm asking because there certainly are issues to be aware of when you start fry in a restricted breeder net.
If you hava another tank, or five gallon bucket I'd make this suggestion, purchase a plastic pasta colandor and place it on the top with at least 2" of water in it. Place your female livebearers in the colandor and when they are born they will go into the tank or bucket. You can raise them in safety and with out crowding while controling food intake. In a bucket, fill with old aquarium water place a air driven seasoned sponge filter in and a heater.
Either way best of luck and Happy Holidays.