Dear Jaiprakash,
Just check in COR6N which search help is attached with Batch field. If it is same MCH1 then you and write enhancement in the Srch. hlp. ext. to show your custom search help only at time of COR6N else delete. as you can see sample code in that exit.
Now for custom search help you need to write custom search help exit for filter values as per Batch selected in MIGO. and for getting material document number in exit can use import/export statement.
Demo on Search help exit for the material
Regards,
NB