Eveery is correct in telling you not to break up a bonded pair. Gliders get very attached to each other and can actually grieve to death if they are separated from their colony members. Even tho Kadi may not be what you need, she is certainly what Nibbler needs. And Kadi needs stability in her life.
There is no guarantee when getting any glider they will be cute and cuddly lap babies. In fact, your chances of getting another just like Kadi are much higher. So why not keep her with her friends and try hard to win her over with love.
Remember - Im the one with Weasel... I know of what I speak!
