So the db and the LC are 2 seprate entities, the LLC can be managed by just one member , no need for partners. The DBA can be filed under the LLC if you plan to do busiess under a name other than the LLC. if you are creating something different and are bringing in a partner for a new company, then you can create a new LLC and make your exiting LLC a your new partner, managers of this LLC.
you need to work with a company that knows your states rules and laws.. hit my myCorp.com or MyLLC.com to ensure you have all the correct forms.