I think you older one thinks he's a human. It's a common delusion and you aren't going to get him past it. You just have to convince him the new one is a member of your flock too.
With mine I use some hand signals to communicate. Standing facing them with arms up like a Y is move away. One arm up and the other parallel to the ground is turn in the direction of the parallel arm. Both hand above my head is come and get it. It helps if you start by directing them to places you know they're going to go. You can add audible commands too so that if they can't see you you can still call them. Reinforcing the Come command with food will pay off when you're trying to get them out of a pond.
I'd suggest imposing yourself between them and signaling move away when the older one gets aggressive. It needs to be established that he's a member if the group, but you're the boss. Once that gets through, spend time with them together and establish a no. I use a firm No with a spread hand palm down and parallel to the ground about waist height. No is really just stop doing that.
They don't always get it, or maybe don't always want to, but if you use the same interactions with both of them they'll eventually pull together. Especially if you run them around the yard once a day (or lead them, the turn signals work from either direction and following is easier if you've already impressed them). It might sound like lots if wasted effort for two geese, but it does make putting them in at night much easier.