So I recently got another pair of gliders. They're all around the same age with the new gliders being slightly younger, but they are not the same weight. My original pair is underweight and I've been trying to help them gain. It's coming along, but very slowly. After the quarantining time is over, they won't be anywhere near similar weights. I'm worried that the bigger ones will hurt the smaller ones. Should I wait to even try to introduce them until they're more similar in size?
Weights:Original female: 65
Original male: 77
New female: 81 
New male: 105 
The new male is very shy and laid back and isn't the dominant one in the pair, but he's so much bigger than my original pair, I'm really worried that he's going to hurt them.So...what should I do and is there any way to help promote quick weight gain?

We have had gliders ranging in weight from 68g to 210g and never had a problem because of size. Their size usually isn't a factor, while their personalities may be. Just keep an eye on them and make sure there isn't any food dominance going on. Currently we have a male 75g, male 95g, female 88g, and female 109g. They all get a long just fine. The heavier female is somewhat dominant a times, but that's because of her personality, not her weight. She was like that when she was just 85g. :-)

If you feed them a good diet and there aren't any underlying health problems they should gradually gain weight. We weigh our gliders every week and record their weight as a way to monitor their health. Sudden changes in weight can signal a potential health issue, like tooth problems. By sudden I mean about 8 percent of their body weight in a 2-week period. We don't worry about one or two grams difference from week to week.

Once they have had a chance to be together for awhile after quarantine you will be able to see how well they get along.

-Steve-

Thanks for the help, Steve. That makes me a lot more comfortable with the whole thing.
I weigh my gliders weekly as well - my small ones don't lose weight, they just never really gained well. I had been feeding TPG and recently switched to OHPW to see if that'll help.
Thanks again!

Steve has given you some good information.