Using a Macro to create a retention sheet

[leviathan86]

E.g in this workbook I have two sheets, Source and Retention Sheet

My problem is that the source is constantly updated and I need to maintain a historical record of what the value of these cells were, almost like track changes.

So the macro should
1) When executed Copy =Source!A1:U8 and paste values into the retention sheet that would time, date and name stamp the person that run the macro.
2) I would like it so the macro could be run multiple times and retain the data on the next available row.
3) A prompt box that would allow the user to replace the previous entry if required.

I could easily create a new sheet and paste values into there using a macro, however, that could just build too many sheets.