To get the sum of the Default Values of a Property
Click the plus sign next to the Owned Parameter property to edit it.
If you cannot see the Owned Parameter property, make sure the Expert mode is enabled.
In the Body and Language dialog, select Language > StructuredExpression.
Select Create Operation > Operation from Model > Reduce.
If you cannot see the Operation from Model operation under Operations, make sure the Expert mode is enabled.
If you cannot see the Reduce operation, make sure the Apply Filter box is not checked.
Insert the following script as the Body for the Script:
arg1+arg2
Click OK.