2nd Xbox-X in the house

Do both of us need to own a copy of the game to play simultaneously?

You rock this worked. thanks.

If you own the game as well as the subscription you need to set the Xbox Series X as the Home Xbox in that way all profiles including your daughter's account will be able to play the game.

Since you own the game or subscription you won't be needing to use the Home Xbox console, you can play the game without any issues since the license is on your account.

Once you were able to set the Xbox Series X as Home Xbox make sure to sign out.

She is signed into the new xbox and playing:

When I log into the original and Home box:

You are already playing this on Xbox Series X

You can play only one place at a time

Play here instead

End your other session

Hi WillPtx, I hope you're doing great out there despite the issue that you're experiencing. I am an Independent advisor and I am here to help you in regard to your concern.

If I may ask, what is the exact error or issue that you're experiencing whenever you're trying to play together?

Also, Just a friendly reminder though that setting up a family setting on https://account.microsoft.com/family does not mean that the game and subscriptions will be shared to their account, it is a feature where you can manage a child account.