Hi Prasad,
Not sure if I understood your scenario completely but have you tried using field- SBDKZ from MRP4 view of material master. In this field if you maintain value= 2 (Collective requirements only) for a component/s for which you want single requisition.
I mean, if you maintain this, SAP will club total requirement for this component from all header materials and raise a single MRP element (PR/Planned Order).
This field is also available at BOM level... pleas check & explore if it helps.
Thanks.
Kind Regards,
Anup