I would like to find a way to dynamically sum values in a datagroup so that
if I add or remove items from the the grou the SUM value is updated.

Example:
I create a list of items in a price sheet.

Widget Parts Price$6
part1 $1
part2 $2
part3 $3

I group them all together:
data group and outline grouip

I want to sum all the parts so that no matter how many parts I add or remove
the Price$ will automically update. Currently, if I add or remove parts I
have to update the SUM() for Price$.