#3 - Aug. 5, 2010, 3:33 a.m.
To merge a World of Warcraft account into a Battle.net account, first log in to Battle.net Account Management, and then go to the Manage My Games section. From there, select Add a World of Warcraft Account and follow the steps to permanently link a World of Warcraft account to the Battle.net account.
You mention that you are unable o log into the account due to a “login is invalid” message, Nosferateau. Is this when you try logging into your Battle.net account, or your World of Warcraft account?