All right so here's what's going on:
https://steamcommunity.com/id/PlutiaPlaneptune is banned on panda for [Little Anti-Cheat 1.7.1] Aimbot Detected. If this isn't right then I advise your brother to appeal.
There is another account which looks like an alt
https://steamcommunity.com/profiles/76561199163093872
If this is an alt account by 'Plutia' then we're going to have a problem removing this ban as your brother will not be allowed to play until their ban is sorted with.
And then we have your account, so
https://steamcommunity.com/id/MomoNeko isn't involved in this.
So I believe they are your brothers. I believe you're innocent in all this but I'm concerned that, if I do remove the IP, that your brother may attempt to bypass their original ban.
I would advise having a talk with your brother and then responding back to this appeal so we know the next course of actions. Such as if your brother is planning to appeal or not and who owns that alt account. There's no mistake about that alt account it belongs to someone within your household.