Upsert: creates the job category's service-task association if none exists, or replaces service_execution_type/service_tasks if one does. Only links existing Service Task Master records (create them separately via the Service Task Master module first) — does not create new service task masters. If the job category has business units configured, those business units are automatically pushed onto every referenced service task master that doesn't already have them. service_execution_type is silently forced to PARALLEL if the company has the Appointments feature enabled, regardless of what's sent.