Mail Merge - Print alternative cell value if first empty

Hi all,

I have a spreadsheet with two columns of names.
The first column has the primary person's names and the second column holds the reserve person's names.

This is set up so that if there is no primary person the reserve will step in.

Using Microsoft Word I want to mail merge letters to each of the primary people. However, if there is no named primary person then I want the reserve person's name to be printed instead. Is this possible?

Hopefully that is clear enough. Any help, pointers, etc would be gratefully received.

Thanks in advance.

I knew that! But forgot to use commonsense, not a first. I can do this but since I need to copy and paste in the most up-to-date information was trying to use mail merge instead. But if I place the third column at the far right side then I can still do the update and the mail merge.

Thanks for the help and here's a teacher's star for you. ;-)