Hey @Stewartwolfe 
Welcome to the Emma Community - you can introduce yourself here if you fancy 
I really like this idea!
I only use my joint account for groceries or when we go for meals together, so I probably wouldn’t use this feature exactly the same way as you… but I can imagine other people would.
I think it could work well between anyone that doesn’t have a joint account though - maybe if I paid for drinks I could then share the transaction with a friend to remind them they needed to pay me back? 