Search on partially duplicated categories

["Lyn St George" <lyn@zolotek.com>]

This should be simple, but I can't find the answer anywhere.
I have categories in this format:
Blue
Blue Room
Green Room
A 'one click' search on Blue Room returns only that, with no 
'green room' mingled in. (incidentally, spaces don't seem to 
matter in MV 3.14-3).

Searching on 'Blue', though, mingles in results from 'Blue Room' 
as well.

I've tried setting co=yes, un=yes, em=yes
Have I totally missed the obvious, or this something that 
really can't be done? Unfortunately, I really do need to 
keep the naming format as written above. 

Many TIA
Cheers
Lyn