Hi @slash, Sharon et al
Looks like the app feature I build (Report Status to Main) does exactly that. It takes a group of items in a detailed board and reports % of completion (like “64% Done”) to a single item in the master board. You can have as many detailed boards as you want. The boards are linked by a column in the master board holding a “MatchID” and detailed boards with [MatchID] in the board title. More info can be found here Monday app with automations released - #4 by basdebruin