Account sharing

Hi there is no way to share between three accounts.

All you can do is:

Account 1, you share Account 2.
Account 2, you share Account 3.
Account 3, you share Account 1.

You will not have games on Account 1 of all accounts, but you can do this sharing.

Put your tag and saves on a usb stick and you'll be fine to transfer the account back and forth.

Hi you can both play the game on your brothers device as long as he's designated as the home Xbox account, Sharing it simultaneously on 2 separate consoles is not possible and depending how you go about things , also against the code of conduct as Randy
said.

I would log in to his account to verify it's still set as his Home Xbox and if it is I would preform a full restart of the Xbox One like the steps listed here.

Unfortunately this is a very unusual issue as most people have at last one other who knows their passwords. You could try skipping the LIVE portion of the account and go straight to A: Microsoft Support outside Xbox with conclusive proof and proof that legal
issues will not occur. B: The Email Provider by providing conclusive proof that the account holder is deceased and that you are married to him, therefore making it your property.

Alternatively, you may just have to start again, which would be a shame.