How do I setup a contact where the spouses have different last na.

I need to be able to create address labels and form letters using contacts
that have different last names. For example, if Jane Doe and John Smith are
married, I have them stored as (first name: Jane Doe & John) (Last name:
Smith). Labels print correctly when formatted with (first name, last name),
but form letters come out showing "Dear Jane Doe & John" rather than "Dear
Jane & John". any ideas??