Brother and I have seperate Xbox's but can't play at the same time.

Hi Zach

Sorry to hear about that, however, unfortunately, none - you would need to set his console as your home so this way, you don't need to be logged in on his console.

The purpose of setting up a Home Xbox is to share your games and subscription within the console, so if you plan to play at the same time, your console will identify you're logged in somewhere.

In case you missed this:

How Home Xbox works:

https://support.xbox.com/en-US/help/hardware-ne...

Two ways on how to share core:

https://support.xbox.com/en-US/help/subscriptio...

Your brothers xbox.must be your home and you can only use your content while connected online

Perks like cloud gaming EA play and ubisoft plus only available to the subscriber

This same thing is happening to me and my brother on two seperate xbox one systems.

Realistically this wouldn’t work, it only works if both of you are sharing on xbox using the home xbox feature and having both accounts on the same xbox. If you plan on playing at same time across two seperate devices it wont work with two seperate accounts.
As mentioned it is advised not to use the same account shared to play at the same time

Both of your kids should have seperate accounts i think

2 Players can play minecraft on one Xbox One console at the same time using seperate accounts. Maybe it also applies to fortnite on xbox series x and xbox one?