I have an Estimate Line Items table that has a repeating field which shows the estimated cost of a task across 5 different quantity levels. The Estimate Line Items table is a child table to the Estimates table, where I have a portal showing that same repeating field. I'd like to perform a sum of all the costs for each of the 5 field repetitions across all related records, and put the result into a Total Cost repeating field in the parent table. I've been trying to use the sum function to accomplish this, to no avail. I've tried a variety of syntaxes but can't seem to get it right.
Can the sum function be used in this way with repeating fields in related records, or am I barking up the wrong tree?