Need Help with Resident Kitten with New Kittens

Hi there!

We have a 5mo old male kitten (named Meeps, our “Big Boy”) that we got at 6weeks when it was abandoned under a porch. We recently adopted two kittens—a 5mo old male tabby named Aiden and a 12week old male black cat named Salem. We didn’t originally intend to adopt two more cats, only the black kitten that was going to be euthanized (bc they had like 25 black cats and they statistically get euthanized at higher rates)…but then we feel in love with the tabby and just couldn’t leave him behind. The 5mo old tabby, our “Lover Boy”, is calm and chill and does his own thing. Our 12week old black cat, Salem, is our “Biscuit Maker” who loves to explore and play and especially EAT, haha. Our resident 5mo Meeps has started to play with 12week old Salem— but can get a little rough. I’m struggling to help Meeps understand that when Salem cries while playing…he needs a break. The play is mostly innocent—but I worry that the size difference (Meeps is about 3x Salems size, maybe even more) and lack of awareness on Meeps part will injure Salem. I monitor their play closely and have practiced separation techniques. It’s also that when Meeps is brought together with Salem—he IMMEDIATELY starts chasing and playing and he doesn’t stop doing that until separated. Meeps isn’t vicious or anything and he doesn’t hiss or growl at Salem. I’m just struggling bc I don’t want our resident cat Meeps to feel like he is being replaced or left-out. The issue is also that I’ve noticed that when I separate Meeps for being too rough—he will get aggressive with me and bite and claw (and not in a playful way). I just want to do the right thing by all of them and so anyone with advice is greatly appreciated. I just want to give them all the love, care, and support they so desperately deserve! I’ve grown to truly love these babies and truly admire them. I should also note that the 5mo old tabby and 12week old black cat are neutered—Meeps isn’t yet (although is scheduled for October). I’m not sure if that plays a role or not.

I’d also like to mention that the flair of “behavioral issue” wouldn’t be my choice—but it was the best option for this that was listed.