Profile during split-screen co-op based on order of signing in rather than account that signed in

When I play split screen multiplayer with my siblings, the accounts seem to be messed up. For example, suppose I am laying a world with my sister and my brother. My sister will be signed into the second screen and my brother into the third. The next day when we play, if my brother takes the second screen he will have my sister’s inventory and be at my sister’s base, and vice versa with my sister on the third screen. It seems that instead of using the accounts of whoever is joining the world on the same system, Minecraft is using the order that they sign in to save the user profiles.