60 grams is waay to skinny! my skinniest glider goes from 90 at her lowest to about 100 grams. atm she still has holiday weight form xmas tho (OOPS!

) so she weighting more 110grams, which is what my skinniest boy weighs. The ideal weight for a glider is about 100-150 grams i beleive, but marie or Jen will have to check that, i get numbers all confuzzled! lol
Try giving her oatmeal with applesauce, you could even slightly warm it tomake it more palantable if you wish but you need to get her weight up.
Have you taken her to the vet to check for parasites too? If they are feeding seperately, and she is polishing off her dinner, she should be gaining weight.
Alot of gliders put weight on in the winter so im quite worried yours weighing so little in the cold. She could be at risk of torpor as her body fat will be quite low and she will be able to feel drafts more then the fatter one, leaving her more open to colds.
Try her with the oatmeal and applesauce and if she stillwont gain the weight, i would recommend a parasite test from the vet.
I hope everythibng goes ok! xxx