I already use family sharing. But family sharing "locks" the library of the person you are borrowing from. On top of that, if you happen to have two copies of the game (1 for me, 1 for wife), there will still be no option to choose which library to lock, ending up with potentially the library the child want to use, already locked.

I appreciate family sharing, but it has some limitations that aren't amazing.

GOG is just "you are playing that one game". Way easier.