Search Tool - find A or B but not C

[Mick Sulley]

I use the search tool to create slide shows for birthdays etc, but 
sometimes I want to exclude pictures containing a certain person, so I 
want to find all pictures with person tag = Bill or Fred but not Joe.

I can do it by creating a search for Bill or Fred, saving the result and 
then searching that for not Joe, but that is a bit cumbersome.  Is there 
a way to do it as one search?

Thanks

Mick