Transfer Ultimate Game Pass to Child's Acct

I signed in from my (Parent) account and followed the process. It is already set-up as the 'home xbox'

Nothing can be transferred between accounts. You can set the console as your Home console and that will allow you to share the subscription with him. https://beta.support.xbox.com/help/hardware-network/console/my-home-xbox He
will need to start his progress over again.

We also have the frozen city scene, went into high street retailer and they suggested that it may be that the Xbox Live acct is registered to a child's acct and the maker of B4(not Microsoft) has insisted that a child cannot access the game, even if a parent
raises security blocks for that game.

Have also downloaded all updates to the game but still no joy. Now having to download software to speak on line to an ambassador to see if the child acct is the problem.

If you bought Xbox Game Pass Ultimate and already own Xbox Live and Game Pass then both subscriptions will be transfered into ultimate and add more time to it

XBox Support cant promote your child acct. When you search up in the search bar on this page it tells you you have to do it yourself. So when you are of age, you should be able to go to acct management, and under the manage acct page there should be a "promote
child acct" option.