Special Proc Key- 80 - Production from alternative plant

Hello ALl,

I person merchandise for which readying works is A and 2 accumulation plants B & C. Currently I know, peculiar pro.key 80 which tin beryllium utilized to nutrient from alternate works similar - I tin bash readying successful Plant A and nutrient successful Plant B. 

But If I person 2 accumulation plants similar B & C - and I person to nutrient archetypal from works B arsenic superior plant  past remaining qty. from works C. 

How to execute this? 

@SAPPP, @ProductionPlanning, @SAP