There is also a chance that the third female may pull joeys from the other two, or that she will also be carrying joeys soon.
Your glider population could jump from 4 gliders to 10 within the next few months.
PLEASE neuter your male NOW if you plan to keep him with the 3 females.
Learn all you can about caring for rejected joeys. You may have to deal with several rejected babies at one time, all needing around the clock feedings 24/7 for several weeks. Get a joey rejection kit just in case.
Hopefully all will go well, but you will then have to deal with finding homes for multiple joeys. If you keep the joeys you will need to separate all the female joeys from the colony to prevent in-breeding with their father (if he is not neutered) or their brothers.
You will have the added cost of neutering all male joeys (add that up $$$$ if you should have several males). If you do not neuter the male joeys they will need to be separated from their mothers and sisters before they begin to mature at about 4 months OOP.
In any event you have a long road ahead and some vet bills you may want to start saving for now. You may also need either a very large cage to house the colony or several cages to separate the males and females.