Formbuilder and multiple links?

Can one link to 2 different tables using DB_DataObject_Formbuilder? I have an account table which holds Credit Card info. it links to the user table on account.user_id = user.user_id and account.account_type_id = account_type.account_type_id. So I want the form to show the username (not the user_id) and the account_type_name (not the account_id). I can get it to show just the account_type_id and user_id (in select boxes), and I can get it to show just the username (by setting linkDisplayFields), but I can't seem to get it to link to both tables. the links are fine, I've tested them. My code: $fb->linkDisplayFields = array ("user_id" => "username"); if I use: $fb->linkDisplayFields = array ("user_id" => "username", "account_type_id" => "account_type_name"); the script tries to select username from account_type! Any ideas here? Thanks, Jacob