New cat, 2 years, was a stray is now attempted to assert dominance with another male cat but was separated and now he's giving us(the owners) pushback?

We are a cat household with 4 different cats. 3 being shelter cats and 1 being from a friends litter. The two oldest are 4(M)/5(F) y/o while the 2 youngest are 2(M)/ 2 and a half(F) respectively. The oldest and second youngest always got into little spats as the two girl cats of the house but recently we went and got another boy.

He is increasingly friendly and always trilling for the others attention behind the closed door. The youngest female yesterday however for the first time ever truly attacked one of my roommates during dinner. She had shown signs of frustration but never gone as far as to lash out at us- ever. When when we got the younger male a year ago. She never took it out on us.

I'm worried this is because the new cat we got is a proper tomcat with rather large jowels and little house experience. He is potty trained and neutered by the shelter of course and his foster home he had for a short time. It was said he got along well with cats in the foster home but was housed alone in the shelter. I do think this was due to some dominance behaviors he exhibited right away. Our youngest male was excited and happy to greet him. What we hadn't expected was for our new cat to immediately bite down on his neck to assert dominance which the other did not appreciate and we separated them almost immediately.

But upon separating them, the new cat seemed to get upset. He did not lash out or growl- I am unsure if he hissed but it looked like it without the noise coming out. I am worried that if he do not allow him to assert dominance as he pleases, he will get increasingly frustrated with us and subsequently stressing out the other cats more. We already had one big fight between the roommate and youngest female- now this.

I'd love some advice, we have the time to try and make these bonds with everyone and willing to put in the effort of course but if it truly thought that this could cause more harm in the end, I want to know before we put our cats through this for no reason.