Welcome to the forum .

First off, you should house all of them separately. Housing males together can lead to them fighting and it is very stressful to them and housing males & females will lead to unplanned clutches. Also, you should get your husbandry spot on and learn as much as you can before you consider breeding. Caring for babies isn't hard but you should definitely have experience under your belt before you bring new pythons into the world .

If the larger one is already gravid you need to separate her asap to reduce the stress of being house with another BP. You just need to keep the temps and humidity stable while she is gravid. Before she lays you need to get an incubator up and running. I wouldn't recommend you letting her maternally incubate since you lack the experience to see if something isn't right. Incubators can be purchased online and some are relatively inexpensive. Once she lays you need to incubate the eggs @ 88-89 degrees @ 100% humidity (but not WET) and they should hatch in 55-60 days.

Hope everything works out.