The most insane and complicated problem ever.

Hey, so, i know I fucked up.
this is going to be long and complicated but ill try to break it down good, hopefully some of you will give it a shot and try to help me and my family.
so lets say there are 3 phones, phone 1 is a lg g3, its my girlfriend's old phone which i used when my z3 was being fixed at the lab, so phone 1 came to me with my girlfriend's chats and when i logged in, also mine. phone 2 is my z3 that got back from the lab and i verifiyed my nember in him and got all my groups + my girlfriends which is fine. now, phone 3 is my sister's phone, also a lg g3 but the lab told her she needs to replace her core, the screen alwasy shuts down and they told her to put a piece of paper at the back to get it to work sometimes, she managed but still needs to be fixed, we'll fix him tommorow.
the problem is, my sister wanted a phone for her long trip that starts tommorow so i got all my stuff from phone 1 and moved it to phone 2, then i wanted her to have the phone 1 so i think she logged in whatsupp on phone 1 and verifiyed herself and then got her groups and my groups and my girlfriends groups, i tried a lot of google drive backup but i needed to remove the photos to backup only the messeages, which was problamatic. i think we tried more things but i cant remember them well, at the end we got to this: i accidently "changed numbers" on phone 1 from my sister number to mine i was stressed and i thought this will move msgs or something, i was wrong, now she has a google backup somewhere with her msgs i think but we earased whatsupp and installed it again, and when she opened it there was nothing....
then she told me she managed to get some time on phone 3 (the one that doesnt work so good) and said that she has her contacts there, but she's not in the groups, I am.. im now recieving her group messages, and im in a need for a way to make things right without changing the number to my sistes and then exiting my groups (because she will get them) and asking the admins to add me again, is there a software of some kind that i can manage certain chats or groups or do something else i really dont know anymore.. its fucked up iknow its long but if someone has any idea, please!!