Hi Nikhil,
You should not have to write code for this. Based on your screenshot it is pretty clear the Item 11 in the order is generated as result of BOM explosion.
There is a standard configuration available in SAP to tackle exactly this situation. Check the Item Category for you delivery Line item 20 "ZO90" has got this highlighted(Yellow) parameter as "X" or "+" or not. Speak to your functional part also.
It should fix the issue.
Incase the config cannot be changed, there is no other way other that writing ABAP code for this. So you may use MV50AFZ* exits or LE_SHP_DELIVERY_PROC or even can use custom data transfer routine.
R