New kitten and resident cat

[2FelisCatus]

We got a new kitten this past week to join our current cat. Resident cat (RC) and the new kitten (NK) were kept apart with scent swapping for the first 48 hours then slowly introduced and fed chicken together a few times a day. They no longer hiss or growl at each other but I worry that RC is bullying NK. They look like they are playing but the RC keeps pinning the NK. I can't quite tell if I should intervene or not? Any thoughts?

Sounds like a dominance display to establish the pecking order. Is RC guarding the litter trays or barring access to food?

They have separate litter trays and RC hasn't been alone with NK so not sure if he is blocking the tray or not. He definitely saw her off her food after he finished his. Do I let him carry on pinning her? Do they need to go through this?

Whenever we introduced a kitten to the household, there was a certain amount of head-bopping and rough play as the kitten learned the limits (bearing in mind we have male cats who are not very bright). However, it was not vicious - no fur flying, no screaming etc. If that happens or you find either cat engaging in regular "guarding" behaviour such as barring access to the litter/food, you have a bullying problem. We also kept them in separate rooms for feeding, so the adult cat did not steal the kittens food.

It's normal - RC will be establishing his authority over NK.

Our boys are 7 and 2 now (we also have a 6yo female) and the older one still pins the younger one and will try and show him who's boss 🙄

As long as it doesn't turn into figuring I really wouldn't worry. My two have never hurt each other and if I think they're getting a bit rough I just call out "oi!" and they break apart and start grooming each other like nothing has happened 🤣