Hi Rich,
You could add a custom data column to your plan to use as an input column for future project investments. Unlike reference data columns, these are true input columns. Only users with the Budget Process Owner role are able to access the Add Column action.
To add a custom data column:
1. In the Planning module, select a plan from the Plan Selector
2. Navigate to the Line Items view
3. Click the Actions button and select Add Column
4. Name the column
Users can enter their own values into this column. The custom column can also be imported/exported just like any other column. You can refer to What's New in December 16, 2015 Release for more information on this feature.
Thanks,
Ngoc Le