Adding more xbox360 users to Series X

So you're saying that if I make more SeriesX-accounts these will be usable on 360-games as well? If so, why doesn't signing in with a guest account work similarly?

The guest account works the same, however, as soon as the guest signs out the account is removed from the console. Fine for a one off log on when say you visit a friend. But since your situation is perhaps more permanent, it needs a more permanent solution.
Hence why I recommend creating an account.

Note that there is no such thing as a 'Series X account'. Any Microsoft account with a Gamertag works on 360, Xbox One, Series X/S and a PC running Windows 10.

Xbox 360 games do not appear to see these users and I'm unable to select them when adding players to 360-games.

User accounts work differently on the 360 (and the 360 emulator on the Xbox One and Series X/S) to the way they do on Xbox One and Series X/S. The 360 had user profiles that needed to be downloaded first.

It's been a while so you'll need to bear with me. If remember you will need to sign in first with this other user you've created, then launch the 360 game. This will download the additional new profile to the console. I think, after this you should be able
to add this player to your game.

So you're saying that if I make more SeriesX-accounts these will be usable on 360-games as well? If so, why doesn't signing in with a guest account work similarly?

I've tried this now, but adding more accounts to the Series X does not help (the same as having guest-accounts signed in). Xbox 360 games do not appear to see these users and I'm unable to select them when adding players to 360-games.

So it appears I need a different solution. :/

Hi,

The Xbox One and Series X/S does not support local users like the Xbox 360 did. All users need a Live account.

They don't necessarily need a Live subscription. As long as your console is set as your Home console, all other accounts can share your Live sub. You just need to make another account.