Can the PRIV_FLG column of S_CONTACT base table be updated using EIM? (Private_Flag is used to enforce Personal Contacts)

No. The S_CONTACT.PRIV_FLG is not part of the user key to the S_CONTACT table. However, it is included in the criteria used by Enterprise Integration Manager (EIM) to locate an existing row in the S_CONTACT table (It is a required column, but not a part of user key). Currently it is not possible to update the S_CONTACT.PRIV_FLG using EIM. For contacts loaded using EIM, the only supported value for the PRIV_FLG is "N". This specification can be enforced by adding FIXED COLUMN=CON_PRIV_FLG, 'N' in the ifb file.