I've just found out if you set a friends/another console as you Home Xbox, and they do they same, you have the ability to game share.
If, for example, they buy trials through their account on their Xbox (which I've set as home), I can then download on my Xbox for use with all gamertags on my Xbox. I could even play in multiplayer with this friend under the same game purchase.
Is this a loophole, which will result in bans, or a legitimate thing to do? Note, xbox support will assit in setting it up.
It would be very cool to make an agreement with someone, to split the cost of all future purchases, and password sign-in would protect your account.