hi Ivan,
in order to have a section that repeats on each page of the subreport you need to create a fake page header. in the subreport, create a new formula with syntax like this
whilereadingrecords;
''
go to the Insert menu and choose Group and then choose your new formula to group on. in the Options tab choose Repeat Group Header on Each Page.
now you've got a fake page header in your subreport. you can put any objects in this header that you want to appear on each page when you preview the main report.
question though...why are you using two subreports for this as opposed to one or zero? if you're using the same data for the main report and the two subreports, you don't necessarily need subreports. you can create the chart on the main report and then use a cross-tab, also in the main report to display the "legend" data.
if your subreports are on different tables than the main report, you could probably combine the two subreports into one assuming that the two subreports are using the same tables and data.