Since you are dealing with living animals no one can guarantee how they will behave. We can tell you what we think will probably happen but there are all kinds of exceptions for all behaviors. They each have their own personality and don't all react the same.
The only reason you need a rooster at all is if you want fertile eggs to hatch. Everything else is personal preference. I suggest you keep as few roosters as you can and still achieve your goals. That's not because you are guaranteed problems with more roosters, but that the more roosters you have the more likely you are to have problems. I don't know your goals or why you want two males, but that seems to be your preference. I'll try to work with that.
One huge factor in integration and in keeping multiple males is how much room you have. I'm not talking about that 4 square feet per chicken in the coop with 10 in the run, especially when you have only a handful of chickens. Can they get well away from each other, maybe even out of sight behind a wall or something? The more room you have the more likely it will go well. If they are shoehorned into a tight space your odds of problems go way up. So, in feet of meters, how big is your coop and how big is your run? Photos can help us understand a lot.
I'm not sure how old your oldest three are but I'll assume they are mature adults. Typically a mature flock master male will accept a young chick as his, even if the colors are totally different. He may help take care of them and protect them, or he may pretty much ignore them. It's pretty rare that he will harm them, whether the chicks are male or female. Your two hens are normally a higher danger to the chicks, especially if the chicks invade their personal space. That is where space comes in. The chicks need enough room to avoid the older hens. It is pretty unusual for a mature rooster to harm a chick but not that unusual for a hen to. It is normal for a chicks to form a separate flock and avoid the adults until the chicks mature themselves.
At some point your cockerel will hit puberty. It could be at three months or it could be several months later, they are all different. That's when things change. The cockerel starts trying to mate females who typically resist, usually by running away. The rooster starts seeing him as a rival, not an offspring. With sufficient room, and I'm talking about a lot of room, it does not have to be bloody but the cockerel's interaction with females and with the mature rooster can still be really hard to watch. This can be when people decide their goals really don't require a male or multiple males, it can be that hard to watch, especially people new to chickens.
So what can you do if you wish to keep both males? You can try to integrate the two chicks with the adults. There are a lot of tricks we use, which ones might be appropriate for you will depend a lot on your set-up and room. This might work until the cockerel hits puberty, it might even work past that. But have a Plan B ready, a place to put that cockerel if things go bad quickly.
You can build a separate pen and keep the two young ones by themselves in there. This may be forever, it may be until the pullet matures enough for you to try to integrate her by herself. There are challenges in integrating a single pullet, especially before she has matured enough to start laying. I know I'm repeating myself but how much room you have makes a difference. People mange that all the time but it can get more dramatic than integrating a few at a time. Chickens are social animals and want to be with other chickens. If she is by herself she may invade the adults' personal space to be with them and get herself attacked.
You can leave that cockerel in his own pen forever and ever by himself or with that pullet. They are social animals so he will not have the company if he is by himself, but he will be alive and not fighting the older rooster.
People sometimes keep one rooster with one or two hens and just don't have problems. This is especially true with breeders through the breeding season, they often have breeding pairs or trios. But a big part of that is that they have mature roosters and hens, not immature cockerels and pullets. They are living animals so no guarantees on any of this, but mature roosters and hens usually form a pretty peaceful flock, even if you only have a few. Immature cockerels and pullets are typically really rough as they go through adolescence. If you can somehow get through that phase you should have a few options with that pullet, but with what you have her adolescence may prove dramatic. I wish you luck.