Find negatives and reciprocal positive values to flag

Hello,

I have a spreadsheet that I cannot find an efficient way to complete this task, so any help would be greatly appreciated. Even if it's just a function and not VBA code.

I need to identify all negative values, then based off of 3 columns (ID, ID_2, Total Cost) find it's reciprocal positive value (so ID and ID_2 have to match, and Total Cost has to have a negative, then a positive in the same amount), and flag them (doesn't matter what the flag is....a 1 in the last column would work). The problem I ran into though was that when there was more than 1 positive value. I'm attaching a spreadsheet for an example to show what values would need to be kept and what need to be flagged.

This is just a small sample out of workbook with about 20 columns and 9000 rows. And because the columns shift a lot, if VBA is used, it would have to read the column headers, not the column position.

Please let me know if any further clarification is needed.

Thanks.