You cannot merge accounts. Also, the email address associated with your xbox live account is irrelevant as far as Bungie is concerned. They don't know or care what email you use to log into your Microsoft account. What you're trying to do, is switch the Gamertags linked to each account, so that your newer Gamertag is linked to your older Bungie account. Right? If that's the case, you'll need to do some account shuffling: First log into your newer Bungie account, using your newer Gamertag credentials. Go to the account settings, and link a new set of credentials to the Bungie account; Facebook or Google+. Log out. Log back into your newer Bungie account using the newly linked credentials (Facebook or Google+) Go back to account settings and unlink your Microsoft credentials. Log out. Repeat this process for your older Bungie account, so that both sets of Microsoft credentials have been replaced with Facebook or Google+ credentials. Now, log back in using the credentials you created for the older Bungie account. Once again, go to account settings, and link the older Bungie account to the newer Microsoft credentials. Now you can log out and start using your newer Gamertag with your older Bungie account.