BattleNet won't link my Xbox account, only my brother's

When I click on the connections tab of my BattleNet account and try to link my Xbox LIVE account BattleNet automatically connects to Xbox LIVE and pulls the information from there to link the accounts. The problem is it only wants to pull my brother’s account even though my account is the one logged into on Xbox(dot)com. Why can’t I manually select which account I want to link? I know the username, password, email, phone number and any other possible authentication I could give for BattleNet to link the accounts but it just HAS to do it automatically and if I were to link my brother’s I’d have to wait A WHOLE YEAR before I could try and link the right account. Why? Just why? Let me have my cosmetics I paid for in Overwatch 1