Margin Calculator Help Please

Is there a way to factor-in column P in the margin calculation?

I do not understand this. I understood from Post #1 that you want to enter the margin:

whereby I can input the desired Gross Margin

Or do you mean the calculation of the price? Column P is already in that: =-(P3+0.3+L3)/(S3-0.881)

I respected all your existing formula when creating the price formula.
For a given margin, the formula gives exactly the price that you must enter in your first workbook to arrive at the same margin.