Ok guys - quickie before i get too involved in what might not work

I have a report and it splits out different currencies and tax
GBP - 5%
GBP 17.5
GBP 6%
EUR 6%
EUR 21.25%
Etc.... (too many combinations to mention)
My reports splits these out -
however sub report question

I have on the sub report 2 fields that are variable according to the tax
lets call them Box1 and Box2 total field Box3

my taxtbl has two field if field 1 is selected the tax goes into Box 1 and if not Box 2 -

Box 3 be a figure

if field 2 is ticked then tax goes into box and added into Box 3

(I have the rules working (ish) )
now Iwant to runt he report - it split out the currencies and the tax and then the sub reports precurrecnyper tax

so GBP 5% will be the main report the sub report(s) I want to split according to the rules

then the next batch in this case GBP 17.5% (different rules)

then the next - is it as easy as I think - just to rfernece to the main report in code on the subreport

its having a fit - is it possible?