How can I copy Due Date into custom filed (with Butler?)

[Klemen GKN]

Hi!

We define our content calendar and social posts in Trello cards and the Due Date represents the date a post needs to be published.

Since it's much easier to work with historical dates in Butler and Custom fields, I'd like to copy the Due Date into a custom field.

I can do that at the moment a Date is Due from now on, but I cannot fill the custom field "Published" for all the old Due Dates.

Any idea?

My main goal is to periodically move one year old cards into another "archive" board or list (not archiving).