How can I separate the xbox games and related progress that my children play from mine.

Unfortunately nothing can be transferred between accounts. So in order for them to be separated they would need to create new accounts and start over.

I created multiple profiles for our family of Xboxes. That actually allows for a lot of control, not just separating games and achievements. For each account, you'll want email addresses established for each. It helps.

I would start with creating all the individual emails. Next, as the parent (and the primary for the Xbox - if it's the Home Xbox), go here: Settings > Account > Family Setting > Manage Family Members> Add to Family. From there, it's easy. Add a new person,
link the email, etc.

Unfortunately, you cannot separate what everyone has already accomplished. The good news, whoever is the primary account holder (Home Xbox), all those games can be shared under each user. Each family member will be able to have different layouts and colors
on the dashboard, etc. It helps to identify who is signed in at any given time.

As for the control it adds, if you set up the emails with actual birth dates through Microsoft (all our emails are MS ones), the system will know if that family member is a child and you can restrict games based on the age. Or you can unrestrict them just
as easily. (There's even an app for it.) Also, you can manage how late any child can be on the system or who can add them to their friends to avoid the questionable few out there in the gaming world.

I hope this helps. Merry Christmas to all!

Thank you for the response. I just wish it was more clear from the start what I should have done. The xbox allowed us to set up multiple profiles but only the one xbox live account could play online games. It seemed silly and excessive to have to buy separate
xbox live accounts and the games when often a child would only play the game for a short while before losing interest anyways. So that led to what in retrospect was bad practice. My kids were too young to need or for us to want them using email at the time
and of course the time flies when your three kids are growing up. Now it is an awful mess and they are not happy one bit! Learn from our mistake please. And I hope that Microsoft considers this to make things better. How many other families must have fallen
into this trap?!

Please be aware many games require separate accounts to play more than a single player.

I would recommend you make them their own accounts, you can set them not to require a login on the Xbox so the children can just choose their own. That way their game progress, which is also saved to the account, is also their own

Unfortunately there is no way to transfer game saves or progress from one account to another. In my home my children play on my home console and can access gamepass as long as they are on that console