It would be very helpful if subitems had column footers like the main items, we are having an issue trying to calculated hours and cost rates for employees with different pay rates and it would be great to use subitems for this but we cannot find a way to add up all the costs and mirror to a main item.
The out-of-the-box solution is to use the “Show summary at parent” which can be found in the column menu at your subitems. As the summary in the parent item will be a new column (mirror) it might be difficult to use that summarized info in calculations and automations. Alternatively the app Rollup Subitems summarizes the subitem data to existing columns in the parent items. See: monday.com: Apps Marketplace or the full instruction video at RMB and RSI video.mp4 on Vimeo