So the way PS4 game sharing works at the moment is
The reseller has to pay 58% of the price
The phantom has to pay 25% of the price
The ghost will has to pay 17% of the price
If you break it down fairly by using %, but I think rather than adding the different amounts, the 35-25-10 rule looks real good
So now from my standing viewpoint on how PS4 GS works
The 3 people pay up, host gets game
The phantom goes first, makes it primary PS4, DL game
Then the Host/Reseller reset with account deactivation, and starts their process
The locked or ghost gets the info, can't have friends or earn trophies, but can enjoy the game until they sign out of the reseller account
If 2 people want to share just as a reseller/phantom it will go the $40-$20 route, 2/3rd by reseller, 1/3rd for phantom
(I'm just spit-balling here)