my Box is downloading games me nor my brother purchased?

My brother is the one that purchased the game. However my dad can play it as well with out being on my brothers profile, or my brothers X-box. so please explain that

Okay, so please correct me if my understanding is wrong (And I will be considered the master account, brother as secondary):

A)When I do this, all the accounts have to be housed on my XBox. Immediately after doing it, they can go and re-download their accounts on their own X-Boxes that same evening (as they likely would)

B)My brother will no longer be able to use his credit card for purchases, but will retain the ability to use prepaid cards.

C)All accounts except my own will have a mature restriction. (Can this be lifted on my brother's account by me?)

D)As I will be in my house, the nephews will be in their house, and my brother will be in his, purchases will work just as they did before. Things bought by me work for me only, nephews purchases work for nephews only, and brother's purchases for brother
only.

Hi just thinking, x box A is linked with my brother’s account who has the game pass. I think my brother hasn’t bought the game, but with x box A being linked with his, I was able to get the game. X box B is linked to x box A but not directly linked to my brothers x box so that’s why it didn’t let me get the game. Problem solved I suppose.

I purchased the same game on my Series S and my little brother was able to download on his 360

I have somewhat of the same problem but it’s telling me to buy to game again. It pops up in my order history but won’t let me download the game. I purchased it from fifa 21. The same thing is happening with my brother. We both bought the ultimate edition.