I have 3 gliders. 2 girls and 1 boy. One of the girls is very large, one is very small. The male is in the middle. I give all 3 of them treats as best I can at the same time. The male will always finish his as quickly as possible and then try to steal the rest of the female's treats. This leads to a TON TON TON of loud crabbing and hissing.

I hear crabbing at random points throughout the night as well without treats. There is PLENTY of food but the male will almost always try to take food out of the female's hands. They always crab and hiss at him. No one has any wounds or bite marks and whenever I try to catch them in the act I never really get to see it. They are also always asleep in the same pouch together during the day so I know they all like each other enough. I got them all at the same time from the same breeder.

I've tried to supervise and stop him from taking their treats by pushing him away and I've also tried to watch them eat to make sure everyone is being allowed to eat since one of the females is super small.

Is this normal or something I should be concerned about? Is there any way to deal with it properly?

You could take him out for treat time.

As far as the noises in the night, I would put two to three feeding stations in your cage on different levels and locations.

That way he can't hog all the food and neither can your larger female.