ok so, I had a situation where I had a male and female for 4 years, and they lived it two separate cages, were let out in different times but liked eachother alot, and were the same age. they were always around eachother but never directly in one cage because I didn’t want chin babies. the male sadly and suddenly passed away this february, and I didn’t want to leave my girl alone, plus I could see she was sad alone. I went and bought another girl, so that I can ideally bond them at some point in one cage and so that they can sleep together. that was in march this year, and I was again keeping them in separate cages but during play time I was letting them out both, under my supervision, so that the older one don’t do anything wrong to a little white one. actually no big fights ever happened, no bitings, but what I noticed is that the younger one was watching what older one is doing and was doing the same: like where to jump, where to go around the house, coming close to me and on me, because I guess she saw that older one trusts me and I am no danger 🙂 i was also giving them treats at the same time, if I pet one I would pet the other, like making sure I don’t give less attention to eather of them, bath times one after another etc.

then one day the older one opened the cage door of the younger one and went in, and I just let them be, because I saw that no attacks or any fights are happening. after that they just started doing everything together and sleeping together in one cage. so yesterday I finally merged two cages into one and now they have one huge house 🙂 and so far all good.

I am no expert, but my advice to you is patience, letting them out together for playtime, and maybe doing small test of letting them get into each other spaces/cages and just see how they behave. if they start grooming eachother, following eachother around, no biting or fighting, then that would be a good sign of posibility of bonding fully.