You can easily accomplish this with an import action. You can also do this with formulas and let them override but I'll tackle the import action here for you.
Step 1 - Enter the base values. In this case I've added a growth % by country by month based on your example.
Step 2 - Create a saved view that has the data you want to import. In this case we only want months, countries and the "base" assumption.
Note: I used system modules to filter dates and countries. You should do the same.
Step 3 - Create an import and use the saved view as your source. Under the scenarios mapping make sure you map base to whichever assumption you want. In this case I mapped it to Upside. If you want to also copy to downside, you have two choices. Run the import again but point it to downside or create another line item that is a copy of the base so you can map it to downside.
Step 4. Audit your results. We successfully added growth % to the upside as a "seed".
I believe, In your case, if you implement the way @JaredDolich explained it should solve your problem.
However there is another way of achieving this by taking advantage of the functionality called "Bulk Copy". It is really helpful for one time activity. It might not work in your case because of below reasons :
This functionality can only be used by admins. So if the push from one list item (Base) to another list item (upside) is one time activity or end users don't need to do the push and the change is throughout the model (and not the module specific) then you as an admin can achieve this by a simple click
Step 1 - Go to Versions and Click on the Bulk Copy
Step 2 - In the dropdown pick the Scenario list and select your source and targets
In your Cases Scenario List -> Source is Base And Target is Upside
There is a multiple way to do the Scenario planning. You need to create one Anaplan version for scenario planning and a separate list for scenario planning. (It will safe some model space). Only one thing you should keep in mind that all input module data must copied to your Scenario version then only you can analyse different scenario.
** You can use BULK COPY option, but it will work perfectly for current year, if you have more than 1 year time dimension then it will override the value of past year
1. Create System module to control and for scenario selection.
2. In your input module Add two extra line item to control the scenario value so in this method once your what-if is activated the it will take what-if value else your original value.This line item will be flow down to end or for all calculation.So it will have direct impact on P&L.
Final Volume: IF NOT 'SYS_What-if'.'Activate What-IF?' THEN Volume ELSE Volume * (1 + 'What-IF Volume')
3. Create one more module with scenario as a dimension with existing dimension(Here Product)
In above screenshot, scenario is a separate list.
4. Now once you active What-If and select the Scenario version, You will see impact directly.
One BULK copy will work when you want to copy data from one list item to another within the same List. So if your Base & Scenarios are part of same list then it will work perfectly
Second It is an admin activity and this type of action can't be automated. There are ideas that have been given to product team to have ability to schedule the Bulk copy but it has not been taken up by the team yet.