Option to store incident number from ITSM tools, like ManageEngine, IVanti

Option to update Incident number in Alerts page, The default servicenow-Solarwinds integration app directly update details in Orion.ServiceNow.AlertIncident,

But with Custom REST API updates are not allowed.

below are my objectives.

1. I am trying to integrate incident number updates from other ITSM tools like Ivanti, Manage engine.
2. I also trying to update ServiceNow incident number, that was created via custom integration,

FYI: Alternate approach to update incident details into alertnotes,, was already explored, hence seeking some guidance specific to the objective.