Summary

The below rule helps in summing up the Original estimate from subtasks and populate it on the parent issue. Any changes made to the Original Estimate field in the sub-tasks will also be updated on the parent issue. 

Environment

Jira Software Cloud. 

Solution

A similar automation rule can be used to sum up original estimates from sub-tasks. 

Trigger:

When Value change for 'Time Tracking'

Condition:

Issue type equals Sub-Tasks

Branch rule / related issues:

Type of related issues: Parent

Then Edit issue:

Original Estimate: {{#=}}{{issue.subtasks.original estimate.sum}} / 60{{/}}