He's your brother is family so even if she may have fallen out sometimes you just gotta help out. sounds like you have an ideal situation you keep making videos for kapla he makes them for city blocks I would advise that you don't mention each other or anything like that as in your brother's so the both organisations don't know you're competing against one another for their stuff. No reason you both can't get paid but I would suggest that perhaps instead of paying him YouTube revenue you offer to help him get set up and start doing his own channel at no cost similar to how he helped you when you started your channel.

I would suggest he didn't money out of it and try and get him set up so he's making his own money but make it clear to him that you never gonna want to claim off his. what he does on his channel is his, what you do on your channel is yours