Custom groupings&subtotals in pivot table

Hi all

I have a pivot table challenge, that I have not been able to solve.

I have a lot of sales transactions of which I have made an excel 2010 pivot table.
It shows me sales over time on Sales representative (SR) and products (and subproducts).

For informative purposes I would like my products to be grouped in order to achieve som sort of subtotals.

Group 1 contain products 1-2
Group 2 contain products 1-3
Group 3 contain all products (1-7)

I have only been able to get subtotals for product 1-2, 3 and 4-7 which does not fit my purpose.

(I will be able to modify my transaction data to accomodate at solution)

Any help would really be appriciated :-)

I have attached a workbook to better illustrate my challenge.

BR Michael