Copy a Mirror Column(numbers) to another column

Hi - I have mirror columns in my subitems. I need to roll up the summary to the parent item and then use that summary in a workload widget, however you can’t use summary mirror columns in a workload widget. Are there any free apps that will allow me to copy the result of a summary mirror column to a regular numbers column?

I do not have(and cannot use) Make or Zapier. I am looking for a free solution if possible.

Thanks!