You dont need to do that. The home machine is allowed to be online playing. Just not using the Home PS4's users account. But you can still play his/her games because it is the Home system.
But if you're "online playing", that means a PS+ account while the dude who originally bought the game is already signed in to his PS+ account. So are you talking about a second PS+ subscription for the home person to use the locally loaded games online?