IF and INCLUDETEXT in mergefield

[Anne Troy]

I need to alter this merge field:
{ DDEAUTO GoldMine Data CONTACT2->USERDEF01 \*CHARFORMAT }

I have always totally sucked at merge fields. I need for this:
If the value returned by this mergefield = "G", includetext c:\gee.doc
If the value returned by this mergefield = "B", includetext c:\bee.doc
Else, don't even show the field and suppress any line it might create.

I'd pay for this answer!
~Anne Troy