I am regret to inform you that it is no possible to insert more than one email address for ICOM_BKG_MAIL_TO and ICOM_MAIL_FROM setting.
As I have mentioned that the User ID of all settings in Internet node of INI Maintenance Module must be "All" so system will not allow user to assign it to a specific user. Thus, you cannot setup more than one email address for the ICOM_BKG_MAIL_TO and ICOM_MAIL_FROM setting in Internet node of INI Maintenance.