sale order reflecting in production order

Hai All,

I have following scenario.

I have two plants A and B. A is depo and B is manufacturing plant. product after manufacturing is transferred from manufacturing plant ( B) to Depo ( A) through stock transport order. Now sales order is placed on depo as the sale happens from here. stratgey group 50 is maintianed at both the locations A and B. Now the requirement is passed on to manufacturing plant from Depo through special procurement. Now when we do MRP run planned order gets genereted at B manufacturing plant. When I am converting this planned order to production order sale order number is not reflected in the production order. I want sale order number to be reflected in production order. what strategy group i have to maintain at plant B i.e. manufacturing plant. Kindly guide me what to do.