How to determine if a Partner Function is deleted inside BADI COM_PARTNER_BADI

I have a requirement where in when a partner is added/changed/deleted in Order, then that partners corresponding contact persons need to be added/removed.

I am trying to achieve this functionality through BADI COM_PARTNER_BADI and method COM_PARTNER_MERGE.

Problem I am facing is, I am unable to determine whether the partner which is returned in IS_PARTNER_WRK, is a deleted/changed/new partner.

As far as I have seen, there is no flag or indicator which tells, which action is currently being performed (Add/ Change/ Delete).

Could you please let me know how to identify this action within BADI.