Please note that you can only have 1 AC subscription per Account (username). However, you can have multiples of other Turbine games, and multiple Turbine games associated with a single Account/username.
Adding DDO or LOTRO to an Existing Turbine Account
If you would like to add a subscription to an existing Turbine account, please contact the Account Management department via phone or web form and they will be happy to assist. Information for both contact options is in my signature. We do apologize, but we don't currently have an automated option to do this on the website.
You can call or email. Information for both is in my signature.
Email turn around for assistance with this is expedited (generally within 1 business day), as long as you contact the Account Management department by submitting a ticket from this page and in the "Type of Issue" drop down menu select: "New Free Account Key Request"
Be sure you're submitting the request on the support page for the game you want. If you want a LOTRO key, submit a LOTRO request page. For a DDO key, submit a DDO request.