Total Vendor Balance in Z-form of F.18

Hi,

We use F.18 for vendor balance print. But according to client's requirement we have copied form F130_CONFIRM_01 to ZF130_CONFIRM_01 and made changes as per requirements.

But client requires that total balance would be come first at the beginning of MAIN widows and total balance for particular vendor is calculated after print of line item table at the end of the page  in standard program SAPF130K.

So, What should I do to print total vendor balance in very first of the page without changing in standard program ?