Dynamics files managed by Makefile

Hi all,

I'm stuck for several days with writing a Makefile with source files 
dynamically generated. This problem raises because of a bug in a 
compiler when a fortran file uses too many modules and I have to split 
it automatically. The original fortran file is dynamically generated too 
but with a constant name.

So I have a main file automatically created by the Makefile: master.f90

This file will be splitted in master_1.f90, master_2.f90, 
master_3.f90.... etc (number of file not known), each of them is a 
fortran module and master will be rewritted to use these module. This is 
done by a special target and a bash script. It works.

But I'm unable with make to get a list of these new master_x.f90 files 
for the compilation, seams that my variable:

SPLIT_SRC=$(wildcard master_*.f90)

is always empty and only evaluated at the startup. I would like to 
obtain a list of targets with:

SPLIT_OBJ=$(patsubst %.f90,%.o,$(SPLIT_SRC))

Thanks for your advices.

Patrick