Change custom field values based on Epic change

[NSEU DevOps]

Hello,

I am trying to work out the best way to meet the following requirement using Jira Automation:

The custom fields "planned closing version" or "fix version/s" of an Issue within Epic" should change automatically and accordingly if its Epic "planned closing version" or "fix version" is getting changed.

However, it should be possible to change the "planned closing version" and "fix version" of an "Issue in Epic" individually without any effect on the other "Issue in Epics" or the dedicated Epic itself. 

To simplify

1. If the custom fields "Planned closing version" or "fix version/s" are changed  in an epic the subsequent child tickets can change automatically.

2. Changing the "planned closing version" and "Fix version/s" custom fields in the epic can also do the opposite and not affect the issues within the epic itself.

Am I right in my understanding by focusing on rule 2 first, as this is the one that can be automated. Whereas, rule 1 would be done by a manual trigger?

Thanks

[Stevan Mandić]

Trigger: when (field) value change for....

Condition: issue type equals epic

Branch: (related issue) For: Children

----action: edit issue (select your fields).

This will change values in all children issues when epic field value is changed 

If you edit onechildren issue field manually, nothing will happen with other issues in epic or epic itself