Your second proposal is by far the more elegant solution of the two. You can
use a conditional field construction, which you must enter by hand,
substituting your own fieldnames and using CTRL+F9 to set the field boundary
pairs.

{IF{Mergefield Field1} <> "" "{Mergefield Field1}" "{Mergefield Field2}"}

Did you ever get an answer
I'd like to insert a field into MS Outlook contacts so that we can enter a salutation
Then when we do a mail merge - can pick up from there rather than first or last name
   
    ----- Kathleen Badeaux wrote: ----
   
    We are trying to personalize a mail merge and I was
    wondering if either is possible
   
    To have a field on the salutation line that would prompt
    you to enter a name on each letter without changing all
    the merged letters to reflect the same name
   
    or
   
    Have two fields in the salutation line and if field a is
    empty then to automatically enter field b in its place