Adding a Sub Report

I have a database which includes the fields cost code, cost type, estimate$
and actual$. I have report built that depending on the contract number a
report is generated with the applicable cost code/cost type combinations and
$$ values. Presently in the detail area of the form it pulls up all
applicable cost code/cost types with their costs, but I need to put a summary
of the $$ in the footer of the report for Distributed Cost, Margin, TSF and
Admin. The problem is that these 4 also have associated lines in the detail
field. I want to NOT include them in that area of the form, but put them in
the footer section.

Any suggestions?

Laurie