In our case, they manage themselves. They're not lap cats at all so there's no competition there and I honestly can't imagine them competing over anything. The highest shelf on the tallest tree, for example... When one of them is up there the other one stays on the shelf below or gets up and the other comes down or they stay both up there for as long as they can manage but I've never heard a single hiss or seen any aggression. Quite often it's Lily who gets the upper paw and she's only 9 lbs (Noha is over 15) but they never fight over anything at home. They eat their wet food from two bowls and here Noha usually picks his and Lily switches to the other one. Sometimes they rest separated in different parts of the house but that's really an exception.
Right now they're playing upstairs with something I can't identify so just waiting on it to be identified as it comes crashing down