I have a simple database structure where each “item” has:
- Value 1
- Value 2
- Summed Value
I’m putting Value1 and Value2 in inputs in a repeating group. The idea is that the “summed value” will be created when the user clicks the “save” button.
I can get the list of the summed values to appear on the page thanks to @gaurav’s wonderful RepeatingGroup Tools (bdk) plugin:
…but I can’t figure out how to save this list of summed values down to my database. I thought it would be as simple as “make changes to a list of things” and then change each item’s “Summed Value” to the corresponding value in the Column 3 List…but no joy 
Am I missing something obvious here? Basically trying to update a value for each item in a list (my items) with a list of value from another list (Column 3 List).
Any advice would be greatly appreciated 