Forum Discussion
Follow the instructions here.
After it is completed on both ends, you can log out of the other one's account and back to your own, just don't delete either account from either console. No further login will be required to the partner account (which is much more convenient compared to Sony's system regarding shared accounts).
For subsciptions, while both parties can use the benefits, there are some restrictions - you can't actually claim XBL Gold games if your account isn't the one with the sub. However, you will be able to use all multiplayer functions (and of course you'll have access to the Gold games when your buddy claims them).
As for EA Access, again, downloading through the Access Hub app won't work if you're not the one with the sub, but if you directly search for a game in the MS Store that's part of the Access Vault, the Install button will be there.
Thanks a bunch lads. Ill put this to good use.