If you have to receive free quantity always with regular supply then we have to maintain the following steps to generate the second line item automatically in Purchase order
OLME- Discount in kind-Define & assign discount in kind schema-Maintain free goods schema
Here, Define free good schema and assign your schema group of vendor, Then assign the procedure created NR0001 & then save.
The above step is very important for the free goods scenario to work.
Create Material master data MM01 , in Purchasing view maintain quantity free goods field by ‘2’
In Vendor Master XK01, in purchasing view check Grant Discount in kind
Create Info record ME11 and maintain quantity free goods with validity period in conditions
Hit on free goods to maintain the condition records, you can also maintain it by MBN1 t-code
Create PO ME21N, Enter the Details see the result as per the free goods scheme 15 Qty becomes free automatically in second line item,