add notes with acknowledge feature
Google Drive (sheets) already has this feature. Basically, instead of a note, you add a comment to a cell which the other person can respond to or acknowledge. So, if my roommate gives me a receipt and I disagree with a charge, I can remove that portion of it, and state my justification for changing the subtotal. That way, (s)he knows why I did it and knows to come talk to me if it doesn't make sense (e.g. where are those batteries you bought? I need some.)
Thanks for the suggestion! I know the feature you’re talking about on Google Drive/Docs/Sheets, and it does come in useful sometimes. This probably won’t get added to our comments in the very near future (it’d require some cross-platform work), but I’ll pass on the suggestion and add it to our list of possible improvements.