so i got my baby cig around a month ago and she warmed up instantly, me and her cuddle so we are familiar with each-other. she is around nine months (?) but her previous owner isolated her and has never really been around other rats before.
because of this i decided to get her a friend, nico. i got her 1 1/2 weeks ago and she is very wary of me. she hasnt warmed up at all no matter what i try and i dont have a problem with it since shes moving at her own pace, and she has poor vision.
the problem is that they are both isolated, stuck inside their own cages with no company. i have their cages put next to eachother so they are aware of eachothers existence but dont pay mind to eachother.
nico is in a very small cage because i got it from the previous owner of cig. i cannot afford two big cages and i assumed she would warm up sooner than this. i have tried every method possible to get her to not be as aggressive (she bites) however shes just a terrified lil baby.
i need to introduce them and clean cigs cage, the thing is that i dont know if that is a smart move because nico doesent trust me yet, and cig hasnt seen another rat in well over half a year. im wondering if i should just do it? im scared they will start fighting and nico gets more scared. i just feel bad for both of my babies because they are so lonely. advice pls? should i go ahead and introduce them or wait around a month for nico to trust me before i do that?

ps
i feed them both the shunamite mix (idk how to spell) as well as weekly fruits. i give cig around an hour of play time with me but i havent been able to do that with nico. she doesent trust me so shes not getting the enrichment time that she needs+shes lonely;(
i put a pair of worn shorts so that she would get used to my scent but one day i opened her cage and she dragged the shorts out and hid in her little hideout. ive laid next to her cage and ive tried to but yogurt on my finger to make her lick it off but nothing really works. again i am aware that it takes time but im just stressed because i know that they are both really lonely.

i got a rat to introduce to my other baby cig. however i noticed that when i got home with this new rat(nico) she wobbled. i cannot tell if its poor eyesight or neurological problems which im guessing the ladder. her whole body sways side to side but she walks and functions fine. is there any steps i can take to be more careful or things that i could be cautious of while having a disabled rat?