How to automate a multi-select user field from Epic to child issues in company-managed projects?

Question

I'm trying to edit an automation for the multi-select custom field so that when that field is modified in an epic, it finds all the children issues within the epic and edits that field in the children to match the epic.

For example, Epic has 3 values in the custom user field: QSR, CPR, MBR. I want the automation to fill in the custom user field for a child task so that it matches the parent Epic issue. Meaning: QSR, CPR, and MBR are automatically added to the custom user field of the child task.

I can't tell it to always fill in QSR, CPR, and MBR because every Epic has different people attached to it.

The json I have now is this below, but I know I need to address the field's array values. I just don't know how.

{
"fields": {
"customfield_10049" : {{issue.epic.customfield_10049....?}}
}
}

Nina Barley · Answer

Naturally, as soon as I posted this question, I figured out how to do it, thanks to another user's post (which I have since lost, so can't give credit where it's due).

Here's the automation that worked: