Adding possibility to add SQL row as a column could be also a workaround to achieve that. Right now (BPS 2020...434) is is only possible to add instance number from system fields to mass notifications.
The mass notification functionality will be rebuilt in the WEBCON BPS 2021 (soon). There will be an option to define many different types of mass notifications with different templates (user-defined templates) and different conditions (based on business rules).
