How to remember/save some values before refresh

Hi everybody,

I would like to ask you for some advices.

We would like to save some values before refresh. It is like you have mistake in your data, you need to remember it and make some calculations using this value after few weeks.

But you have to immediately repair the value. It must be correct, no errors. But I have to know - who, which department and other information make mistakes and how often.

But in report (exactly in database source) mistakes must be repaired.

Do you know, how to save the "error value before refresh" in new column before the correction?

Is it possible?

Thank you for your help.

Marie