How do I add additional Household Names?

My organization is currently using the standard NPSP household naming conventions for formal and informal greeting. We would like to add a third option for "Address Name." I've created a new field in accounts and have tried using the process builder and workflow rules to populate the field with Salutation (which I have converted to a text field) + First Name + Last Name. No matter what I do, I either get an error or the formula doesn't process. What's the best way to add an additional household name option?