GARP FDF

I am having an over 40 memory issue here..I can't recall how to create a
new GARP fdf (for the GFS gridded MOS) that will ignore the entries in
the default GARP scalar and vector fdf....like MSL Press which is not in
the GFS gridded MOS.  Does anyone know how to get a GARP FDF to ignore
the Default..without resorting to deleting Defaukt?

Thanks,
Robert Mullenax
CSBF Meteorology