Valve is improving how Steam Family Sharing works—but if your brother gets banned for cheating, so do you

pcgamer.com:

Family Sharing is a pretty great feature on Steam: Simply put, it lets you share your game library with friends and family, so if you and your brother and your mom all want to play Helldivers 2, for instance, you don't all have to buy it separately—as long as you don't want to play at the same time, anyway. That restriction was removed today, though, as Valve announced a pretty big overhaul to the system that combines Steam Family Sharing and the Family View parental control system into one big package called Steam Families.

Steam Families functions very similarly to its predecessors, but makes a handful of improvements, the biggest being that members of the family can play different games at the same time. 

Under the old system, if someone was playing a game from your library, no one else could use that library at the same time. Now that limit is gone: You can't play the same game at the same time, but you can play something different. Each member of the family group will also have their own individual saves, achievements, workshop files, and other features.

The new parental controls also enable parents to monitor what their kids play on Steam, and when, and provides access to «playtime reports» so the adults in the room can see what exactly the kids are getting up to.

There's also a new option aimed at simplifying the process of purchasing games for children: Instead of having to purchase a gift card for their kids or hand over the credit card (which, as someone who once rang up a very large bill in my mom's name, I can tell you is not a great idea), child accounts will be able to simply request that an adult account in the family group pay for whatever's in their shopping cart. Adults can then approve and pay for the purchase from their mobile device or via email, at which point the games will be added to the child's Steam account.

The Steam Families FAQ provides a real-world example of how the new system works:

Let's say that you are in a family with 4 members