Xbox All Access account created, but no purchase made due to sell out

Unfortunately only the bank has the competence to help you.

You can only request a refund from Microsoft's side if you have access to the account from which the purchase was made. Have you verified all the account you have access to?

Has your child not created a secondary account?

Which console the purchase was made on doesn't matter. It's which account that made the purchase that matters. A purchase made with the account that uses Xbox B will allow users on Xbox A to access the game since that is the one they made Home. While a purchase made with the account that uses Xbox A would allow access to the game on it's Home console Xbox B. While other accounts can play the games on a Home console, sometimes the account that made the purchase has to be the account that downloads the games to that console.

I have made purchases on the account, could it be possible to link the purchases made and say my I.D.? Also one more thing, I have access to the Phone number but it doesnt allow me to log in with only that due to 2FA.

You can't purchase points as your account is Canadian. Only work around that may work is create a new Australian Silver account and use that for puchases. Your Canadian account should have access to the purchases made with the new account.

Okay, hold the phone, because now my brother has access to the gun on his account. So I'm thinking it was just a glitch due to Xbox Live having issues and the dlc having just come out.

So the answer is yes, all the content in the dlc is available to all accounts on the Xbox you purchased it on.