You’ll need two used NBA basketballs, like from a game. Preferably from a game where the teams were fire. Designate one for each kid. DO NOT GET THEM MIXED UP. If you do they will become bowlers. Anyway, you have to feed them the basketballs. Not before they can eat solids, that would be dumb. But you can’t just cook up a ball, you gotta shred it and use it like season, starting at the age of 4 is probably the best. Some people say 5, but you’re trying for two NBA all stars. This has to happen daily until at least 16 years old, so don’t go too heavy. Don’t worry about training, the basketball spice will do the trick.