How To Repair Relationship With Kitten?

I’m in a bit of a pickle. My sister and I adopted two kittens from the same litter (1 male and 3 females) about 2 months ago to add some much needed love into my life. They are 8 weeks old now, and they live in our kitchen when we aren’t home. It is an open floor plan with nothing separating them from us except a wall, so we were hoping it would work out for them to have the option of going upstairs if they wanted to go there at night or something like that… But apparently not!

They keep attacking each other because one will get jealous over food being off limits for his siblings so he tries fighting over who gets access first. On top of that, he keeps trying to bite her tail whenever she walks by him on purpose just enough that it leaves a mark even though she knows better than to let him do it purposely… And then he screams bloody murder every time she does this because “she has been bad again!” He also seems upset if anyone else comes near them while their playing together or sitting on me during naps but isn’t bothered when others come near him while sleeping/eating/playing alone… And sometimes he won’t sleep until everyone goes up stairs although I know full well why… So what do you think? Am I making too big of deal outta this…. Or should I start getting rid of these cats? Please help 🙁 -Signed: