Hello, thanks for reaching out. I'm Ace, one of the Independent Advisors. I can understand your concern and please don't worry I am here to help you.
You can share Microsoft Store games with family members by setting up a Microsoft Family Group. This allows family members to access shared purchases, including games, across their accounts. To do this, go to Microsoft Family and add your child's account to the family group. Once they accept the invite, they should be able to access the game. Please refer the article on Sharing Windows 10 Store Apps with your Family here > https://learn.microsoft.com/en-us/archive/blogs...
Let me know if you have further questions.
Thanks!