Drawing Tables

I am working on an assembly drawing that has a BOM consisting of a
repeat region that displays, amongst other things, the part names and
quantities. This drawing is the generic of a model controlled by a
Family Table.
The same drawing will be used for every machine but the quantities of
some of the parts will vary with the model being built. For example,
the number of bolts used is different with every model.
The values in the QUANTITY column are calculated by the &rpt.qty
parameter and show the amount in the generic model.
I was wondering if there is a way that I can replace the values of some
of the cells in this column to a letter ("B" for instance). Then I can
reference each variation to a seperate quantity table.

Appreciate any suggestions.
Peter