Problem Introductions

Hello dear rat community.
I have 2 rats (R 1 and R2 for simplicity) male both castrated (R1 over a year ago, R2 less than 2 weeks ago). R2 got castrated because he seriously bit R3 during the carrier method and in hopes he wouldn’t have occasional fights (no blood) with R1. Otherwise R2 has never drawn blood. They are born in June 2024. R1 is more assertive and dominant and ever since his castration he never once bit again humans or his brother R2. In november i got a third rat R3 male not castrated born in May 2024, after the death of his only companion. R3 is constantly sniffing R1‘s bum and following him around which is very annoying. I used to put R1 and R3 in a laundry basket for bonding and multiple times i put them in a perfectly cleaned rat cage. 3 of those times were successful and the rats spend a night or two in the cage. All 3 times i made mistakes that led to a serious fight and an injury to R3. The first time I separated R3 for 2 nights and then just put him back in the cage, thats when he got bit. The second time i opened the cage doors on the second day and later i saw them fighting. The third time after 2 nights and the rats cuddling and grooming each other i fed them late from a single bowl and gave little food and and im sure that R1 always starts the fights. When i give little food to R1 and R2 in a single bowl (both need to loose weight) there is never a fight. Should i wait until 4-6 weeks after R2‘s castration and start with all 3 rats in the bathtub and slowly do more or should i again put R1 and R3 in the cage? Recently when putting R1 and R3 in the laundry basket R1 immediately puffs up and starts walking sideways and i separate them a few times but after some time they settle but before there were never problems with the laundry basket. I don’t want to cause stress to R3 by giving him up. Please help. Many greetings, Anita.