that situation happens a lot, if they aren't lineaged gliders I'd def get the dad neutered in the near future.
First time parents are at a higher risk of either rejecting or cannibalizing the joey/s, there is no way to predict if either will happen or not. '
The most you can do is educate yourself, This site below is excellent for learning about breeding, the different stages, weights, rejection, hand raising etc... http://www.suzsugargliders.com/breedingsugargliders.htm
be as prepared as you possibly can be, feed them a good widely used balanced diet.
( give an extra portion of staple, a little extra fruits n veg ) while mom has joey in pouch, which will also serve as the joeys portion when mom and dad start to ween the joey and teach it to eat)
Many people say to give extra protein for the mom but really you need to give extra of everything equally so the diet remains balanced and mom gets what she needs while nursing.
Another AWESOME resource is the breeding 101 group on facebook. It's a breeding educational group and seriously it's strictly about breeding and breeding related questions and info. The group has loads of reputable breeders, new and experienced, it's a non judgmental group with 0 drama. There are 3 simple questions ( i think) you will be asked when you join to get approved, if for any reason you need help with that let me know ( I'm not sure what the questions are ) https://www.facebook.com/groups/breeding101/
Those are probably the 2 best places to learn about breeding, even if this is the only joey you will have and don't plan on breeding more
try not to stress to much, or stress the pair to much