Hi Arabind,
If you want to compare the standard BOM with respective to issue of materials on order then use FM CS_BOM_EXPL_MAT_V2 which will explode the BOM and display all the BOM Components. Whenever user is trying to do GR for the order get the reservations created from RESB table for the order and compare the same with standard BOM items from FM output. In RESB you need to fetch the MATNR, Requirement qty (BDMNG) and withdrawan qty (ENMNG). If requirement qty is equal to withdrwan qty then issue is completed. You need to compare the RESB-MATNR with IDNRK from FM.
Personally i feel not good to put so much restriction in BOM changes and Order changes practically this changes are found in shopfloor. Instead you can avoid change authorization to user to avoid user changing the BOM Components as per his wish list and have authorization for change order at next level and do comparison with respective to order reservations only at RESB table data.
Thanks & Regards,
Ramagiri