How do I create Authorization Group (Auth Object B_BUPA_GRP) for Business Partner group

I have crated one Change Request Type for 3 Business Partner Groups. I would like to create 3 different MDG Vendor Requester Security Roles for these BP Groups. I wanted to control this Change Request Type by security role giving authorization to each Business Partner Group. However MDG Vendor Requester Security role does not have Business Partner Group field as an Authorization Object, instead Authorization Group (Auth Object: B_BUPA_GRP) exists. Now my requirement is how do i create Authorization Group for Business Partner Group