How do I pick-and-match licenses via Family Sharing if multiple friends own the same game?

I have two friends who own the same game, but one of them isn't very active.
And by 'inactive', I was meant to say it was an alternate account.

Both of them own Terraria, but I always seem to be locked out whenever my first friend starts playing << Insert title of some other game >>, which is normal behavior.
Is there any way that I can make it that the Terraria access I've recieved is through my second friend, who's never on (because that would mean I'd have to log out of my own account and switch accounts), so regardless of whether my first friend is playing a game or not, I still have access.

Note: I can log into all three (main plus 2 "friends") accounts in question, but I don't want to be constantly switching between the two (three).

Also, I still want access to both accounts (since not all the games owned by both accounts overlap).

Steam will grant you access to a game via Family Sharing from the first (alphabetically, by Steam display name) owner of the original game. So if Foo and Bar both own the game, you will only use Bar's family share and disregard Foo's ownership of the game as if he didn't own it. Also note that you will only have access to Bar's DLCs. If Foo has some - you will not know of them. If you yourself buy the original game, you will lose access to Bar's DLCs.
Given that you have access to all accounts, my obvious suggestion for you is to change Steam display names to list them in 'most frequently used' - 'last alphabetically'. e.g.:

• Least used account: Ann
• Medium used account: Bob
• Frequently used account: Charlie

This way Ann will get access to Bob's copy of Terraria whenever Charlie is playing.