I am testing this thing with my brother.
- I have not found a way to send him a email to add him or something.
- I have tried to make him log in one of my computers with his accoun, then I have loged with mine and authorized his account: the result is nothing, he don't see my games on his account.
- I have tried to login on his computer and authorize his computer: Success!, now all my games show on his account + his games.
- When I play any game, he receive a warning about me playing the same game than him, with 5 minutes to save and exit. We have not waited these 5 min, but I suppose steam do what it says in the message.
- When we play the same game, he receive the same message.
To allow a family member to use all your games when you are not using your account, he have to enable family mode. Then you login on his computer and authorize his computer and his account. When he login again, he will see all your games. If you play one of the shared games, your family friend will be quit from whatever shared game he is playing.
The unlocking/locking mode for family mode seems both very nagging/useless. It don't seems to activating deactivating it have any effect (other than blocking big parts of Steam when is active), so maybe I don't understand the system completelly yet.
Family mode seems to work effectively as a "protect the childrens" system for Steam. With it a dad could control what parts of Steam a children can use, and lock him from playing. So is somewhat a hybrid "parental control"/"sharing games".