Memorializing cell content

PeggyLang

I have a column that calculates a date based on 'Column XYZ - 127'. This works perfectly. However, if 'Column XYZ' changes then my destination column will also change (obviously). But I want to preserve what the date WAS before it got changed. So I thought to insert a 'Helper' column and copy the date from destination to helper. However, if I simply use a =Destination@row and 'Column XYZ' changes then destination column AND helper column change. I need to copy the date from destination column to helper while ideally the helper column will then not change again.

Is there a function to copy simply the value as opposed to the operation?

Paul H

One way requires a unique row ID auto-number and a second sheet

Main Sheet

Now Create a Blank Sheet called "History Sheet"

Back to you main sheet create a copy row automation, that only triggers if Original date is blank.

Using a column formula index/match back to the history sheet to find the original date