Question about the upgrade...

What you're asking is actually against Xbox Live's Terms of Service and could get your account banned. (See: Marketplace theft)

To answer your question -- No, you will not be eligible.

this is a good question! did you pay for the game? sadly license transfer can cause issues with who owns the game so you may or may not be able to upgrade unless YOU payed for it. let me know ho it goes and ill continue to work with you!

They are not technically tied to the subscription at purchase. What you'll want to do is sign onto your console with the account with the subscription. This is the "primary account".

Move to the Settings hub (do not go through the Guide/start menu) and choose Family. You should see your avatar here. If you move to right, you should see the option to Add Family Member. It'll show your available Gold spots. Select one, and it'll have you
select what account you want to add. You'll need the account's email and password before you can add it to the Family Pack.

You might run into issues if the other account already has an account.

One question about the upgrade. Will it refund xbox gold pass or no?

Good question. I havent heard about the digital upgrade, but with the disc, I think you have to trade it in to get the 10 dollar upgrade.