Condition to allow only if the parent issue matches specified JQL
To add Parent issue JQL condition, go to the transition of your workflow, switch to Conditions tab and click on Add Condition button.
Select JEP - Parent Issue JQL Condition and click Add button
Type JQL that should match for the parent issue, in order to allow the transition.Then Add button
That's it, the condition is added to the transition.
Please do not forget to publish the workflow.