This makes no sense, as if there is no record for the individual then there is no where to set the field at 0 unless you create a new record with the person you just found but then the record count will be 1 not 0.
If you want to count the 0, it won't matter how many 0 you pasted the sum(will_Count) will always be the same with 10 zeros or 0 zeros
Sum should not return a ? if the field is empty.
Sum ( Will_count ) is also not a syntax that will return anything different that just using Will_count. It's like saying "give me the sum of 5" and the sum of 5 is 5 so it makes no sense to use that syntax (but maybe you were posting imprecisely).
Sum ( RelatedTable::will_Count ) from the context of a related table makes sense, it totals up the contents of the field for all related recors.
Sum (RepeatingField ) works as this sums all the repetitions of a repeating field
Sum ( Will_Count ; Jim_Count ; Fred_Count ) also works, but I wouldn't structure my data like that.
You might look into summary fields and summary reports with sub sumary parts. This can produce totals like you describe here for a report and no looping script is required.
In dealing with the above mentioned, I created a loop, placed the Get(FoundCount) results in a table, created new record for each other these instances, then used SUM(Will_Count) for the final calculation.
Thanks for the assistance.
There are much simpler ways to do this.