BPC grand total and Sub total % of grand total question

Hi Gurus

I am trying to develop an EVDRE report.Let me try to explain the problem.

I am trying to develop the sales report of customer and page break and sub total at on sales zone.At the end grand total of all the sub total . SO far life was good.Now as per requirement after each sub total ( just below the sub total ) I have to insert % ( percentage sales of sub total to grand total ). The problem I am facing is circular reference to % sub total.If I try to to copy from another cell then it break when I change the member set. Let me explain by example.The sub total and sub total % are in afterRange. My problem is calculation and display of sub total % just below the sub total.Any suggestion is welcome and appreciated.

NA AL 2

FL 4

GA 6

Sub total YY

% sub total x% ( yyX 100/yy+xx)

LA BR 1

MX 3

CO 5

Sub total XX

Sub Total % y% ( xx* 100/yy+xx)

Grand Total YY + XX