Copy field value from child issue to parent

Question

Hello community!
Trying to use automation to copy "Assignee" field value to my Custom field with multi user picker have some problems.
It could be manual trigger or creating new issue trigger.
I need to co copy values from child to parent, child is "Story Epic", parent is "Feature".
Using automation where:
^if any child issues presented 
^than edit "My custom field" with values from "Assignee" of epic issue.
Searching about copying values from child to parent has no success. 
Thank you.

Misa_ndmltk · Answer

@Proshkin Kirill Hi, glad to help.

Just make sure you use the "Add to existing values" option. Then, in case you run the rule for every child (e.g. issue created trigger), every child should add the value, not rewrite it.

Proshkin Kirill · Answer

@Misa Hello. Thank you so much for you help, it works.
But may I ask one more question.
If we have more than one child issue, and my field is "multiple users", value from second child issue is not added to the field in "Parent".

Misa_ndmltk · Answer

Hi 
You need to use a branch rule / related issues first.

Second, if you are copying from child to parent, your trigger issue should be the child issue. In that case, "if children present" condition does not make a big sense to me. 
You rather need a "If: Parent exist" condition, then the branch. See my example with a "Reporter" field.