Family online playing

You would need to set the console as your Home. https://support.xbox.com/games/game-setup/my-home-xbox

Hello Lance Lane,

Thank you for letting us know that the issue has been fixed. We'll be locking the thread as the issue has been resolved. If you ever require any help with any other issues please feel free to come back to the Xbox Forums for further assistance.
For those reading this thread and if the troubleshooting steps listed above didn't help resolve the issue, please feel free to create a new thread asking for assistance.

Thank you again and have a great day!

You need to designate the console as your ‘Home’ xbox. By doing this you are allowing Gold Sharing, which will allow her to use your Ultimate Game Pass subscription.

For more information on Gold sharing and the benefits of using a ‘Home’ console, please follow the link: https://support.xbox.com/en-US/games/game-setup/my-home-xbox

Designate an Xbox One console as your home Xbox

1. Press the Xbox button to open the guide.
2. Select System > Settings > Personalization, and then select My home Xbox.
3. Do either of the following:
   • Select Make this my home Xbox to designate the console as your home Xbox.

The age Xbox accounts turn into adult is 18 (19 in Korea). This can not be done before that because of how age is permanently connected with the first age you put in when creating the account - so you can change your microsoft age but that won't change your
xbox account age.

Yes, your adult account will need to change some settings if you are currently on a child/teen account.

Have the adult on the adult account go here
https://account.xbox.com/Settings and click on the child's account and allow the option on the first page called "Share stuff people make (Xbox 360: Member Content)" to everyone (must be everyone). Also, on the first page, "Others can communicate with voice,
text, or invites" to Friends or Everybody. And on the xbox one/windows 10 tab the second option down, "Join multiplayer games", enable that. And then log out and in on the account in question on the console/device and that account can play online.

The other accounts may have restrictions put on them for multiplayer.

You may need to create another world and see if that lets you join.