Hi Sarthak,
As you have discovered the forecasting functionality within the current latest release SAS Visual Analytics 7.1 is automated based on the series. You have the ability to do scenario analysis and goal seeking with the forecast. If you wish to manually override a series due to an intervention such as an ad campaign, SAS has a dedicated forecasting solution that is designed to do this, SAS Forecast Server Automates Business Forecasting
A suggestion would be to create a new calculated data item based on your existing data item and use a boolean expression to make the changes to the series as required. You can then create 2 forecast visualisations/report objects one on the original data item and one on the adjusted data item.
Kind Regards,
Michelle
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