I've been there myself lol I had two separate pairs of gliders I was scent swapping n one day my neutered male dove head first into the new girls pouch... I had to do a formal introduction after that and the introduction was successful usually if they are in the same pouch loving on each other it's successful. HOWEVER, A
month after they were all living together in the same cage I was still having problems with one girl from each pair getting into spats. I finally had to separate one of the new girls from the colony. She had pretty bad facial wounds as you can see here
I used this on her face twice a day
and she is healing up just fine, this was today, it happened about a week ago.
We now have a new rescued girl I just got home yesterday who will be Amy's ( the one from above) cage mate. The female that did that to Amy's face is only about 20 grams bigger than Amy but it was still quite an advantage when it came to pinning her down. The new girl Pico weighs the same as Amy so neither will have a weight advantage.
I'm telling you all this because even IF the introduction is successful they still have quite a while to adjust to living together in the same cage and you will need to monitor them closely for a while to make sure all is well.
Weight difference isn't always an issue though, My male is twice the size of my female and those two have never once had an issue. It was just these two girls could not co exist.