Situatie
Steam Families is a feature in Valve’s Steam game distribution client that allows you to share your personal game library (the games you have purchased from the Steam service) with friends and family.
The system is not without limitations, however. Only one device or user can access the library at one time. The account owner is always given preference, but that means if you share your account with your child, only one of you can use the library at a time.
Solutie
Setting up Steam Families is relatively easy, though you do have to jump through a few hoops to get the latest version. The old method still works, but if you want all of the new features, every person who wants to be in your Steam Family needs to go to Steam > Settings > Interface > Client Beta Participation and ensure that “Steam Families Beta” is enabled. At some point, the new Steam Families will come out of beta and this will no longer be necessary, but for now, it is.
Once you have Steam Families Beta enabled, then you’ll need to exit Steam settings and navigate to the Families settings area. This is done by going to Store > Your Store > Preferences > Family Management.
Once here, you can see those who are already a Steam Family member or add new members. You can have up to six Family members, but at any time you’re able to remove someone and add someone else. Do keep in mind that whomever you plan to invite to your Family also needs to enable the Steam Families Beta on their end too. If they don’t have it enabled, they won’t be able to join your Steam Families.
Once you send a request to an account (the recipient must be someone on your Steam Friends list,) they’ll get both an in-app notification and an email. In our testing, everything went back to the email, and the recipient had to accept the invitation via email and then confirm by logging into the Steam website.
The only time it will become apparent they are borrowed games is if the primary account holder logs into their Steam account and begins playing a game. At that point, a small notification will pop up in the lower right-hand corner on any computer using the shared account notifying them that the primary account holder is requesting access to the library. The shared user will have a few minutes to save their progress and exit.
Back in the main menu, the secondary user will see the following entry in place of the usual “Play” option, denoting that the game is shared from the Family library:

Whenever the primary account holder is using their library, the secondary account holder will be given the option to purchase the game so they can continue playing it.