I need slight different bahavior

[Maciej Walezak]

Hello there,

I have rules

a.h a.o a:
        command

a.h:
a.o: b.h
a: b.o b.h

Since in my case the command creates all target files at one invocation, I 
would like to specify something like this in addition:

a.h: b.o b.h
a.o: b.o

which actually amounts to

a.h a.o a: b.o b.h

But I need the two last directives to behave unusually. I need that 'make' 
checks for existence of dependency files (and possibly invokes some other 
commands that create them) but does not invoke command on account of any of 
those dependencies to create targets.
For example, I need that a.o is recreated because of newer b.h nad not because 
of newer b.o, but if it gets recreated (because it does not exist or b.h is 
newer) 'make' should assure that b.o is present.

I know it is strange but ... maybe somebody knows some trick.
--
Maciej Walezak
-GDN-