1. Select your «CompanyName» field and press Shift-F9. You should see something like:
{ MEREGFIELD CompanyName }.
2. Edit the field code so you get:
{ MEREGFIELD CompanyName \ f ""}
3. Drag the paragraph/line break following the field into it, between the "", so you get:
{ MEREGFIELD CompanyName \ f "¶
"}
4. Press F9 to update the field code. You should now see:
«FirstName» «LastName»¶
«CompanyName»«Address»¶
5. Run the mailmerge.
The \f switch tells Word to insert the specified character if the field isn't empty. So, if the field is empty, you don't get the paragraph/line break.

__________________
Cheers,
Paul Edstein
[Fmr MS MVP - Word]