More consistent handling of .csv data when manually duplicating/creating scenarios

Problem statement/pain points:
When creating a new scenario via duplicating an existing one manually (not using Python code), there appear to be currently two ways to make a change to input data in a table of the new scenario:
   1) change data directly in the corresponding table of “Input Data” under “Select Data”.  However, these changes are limited to editing existing rows and columns, i.e. columns/rows can't be added/deleted
   2) delete the corresponding “Input Data” table (under “Select Data”), and import a new one using an updated .csv file

#2 is not transparent to the user.  Given that it is possible to do a lazy copy of the original scenario data by making changes using #1, it is natural for a user to assume that they can upload a new version of the same .csv file to the data panel, import it in the new scenario and NOT have the original scenario data changed.
 
Current workarounds

- Download mytable.csv data (used in the original scenario)
- Make updates to mytable.csv
- Rename mytable.csv to mytable1.csv
- Upload mytable1.csv in the data panel
- “Import to Scenario” from the Data Panel using mytable1.csv
- Rename “mytable1” table to “mytable” in “Input Data” of the new scenario
  -   Repeat the process for each table that needs to be changed

Proposed solution
   - Once data is imported into a scenario, do not keep a reference to the original .csv.  
   - If a table needs to be updated from .csv, require another “Import to Scenario” from the new updated .csv
   (At the very least there needs to be a warning to the user when they upload a .csv with an existing name to the Data Panel, that a number of existing scenarios are being automatically updated)

Benefits/value
   - Avoid confusion and possible loss of data due to user misunderstanding of where scenario data is copied by reference to a .csv and where it is a lazy copy (changing values directly in “Input Data” tables)

# of users impacted/ how often impacted
   - All users who wish to manually change/duplicate/create new scenarios using the Data Panel instead of Python