Date Stamp List Property for Imported Data

A similar concept around date stamps was suggested here: https://community.anaplan.com/t5/Idea-Exchange/Date-Stamp-for-manually-entered-reference-data/idi-p/38423 but I would love to see this for imports too. A problem I've come across is importing data from a CSV without a date column into an import list. There are creative ways to attach time periods (e.g. current week) as a formula-based property in the list AFTER the import, which solves the date stamp problem if all the rows have a unique combination of data. This is not the case for certain types of data and I'll illustrate with an example:

I have a .CSV that has data for on hand quantities - how much of a given part is on hand at a given location. Every week, this data needs to be APPENDED to the list, not updated; this ensures that historical weeks contain the correct on hand quantities. If I were to have the SAME on hand quantity of a given part at a given location as I did last week, last week's row would be "upserted" or updated instead of creating a new row for this week if there wasn't a date included in the CSV (see: https://community.anaplan.com/t5/Best-Practices/Importing-duplicate-rows-into-a-numbered-list/m-p/33840#M118) . This is due to the combination of data in that row being the same as last week, so a date has to be added in the file itself before import. This manual intervention isn't preferable week after week especially with multiple datasets.