The new system gets rid of limits on how many people can play games from one library, makes buying games for your kids easier, and adds new parental controls and sharing options.
You'll need to be in the beta program to try it, which you can do by visiting Settings > Interface > Client Beta Participation and selecting "Steam Family Beta." Then, to create a family, go to the Store page, click your account, then Account details > Family Management > Create a Family.
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