As a joint account holder, I want to be able to create synthetic accounts and use them as my primary debit account, so that I can allocate and track spending per individual in a joint account.
(The above requires the creation of a joint account first)
As in, some kind of virtual/sub account? Or are you talking about something else?
Correct a virtual sub account, for example:
Account 1 (joint account between me and my lovely better half)
Virtual Account 1.a (primary account for me debited when I use my card)
Virtual Account 1.b (primary account for my better half debited when she used her card)
We each get paid into Account 1 and have joint expenses debited from Account 1 (e.g. rent, bills)
Then we allocate spending money from Account 1 into Virtual accounts 1.a and 1.b for day to day personal expenses.
The problem being solved here is allow joint account holders their own personal spending money and independence.
Thoughts?
That sounds good, based on what we’ve heard from Monzo so far, my guess is you’ll be able to replicate that functionality using a combination of joint accounts & virtual savings pots.
I’m imagining each cardholder having their own card & then being able to pool their money into a shared virtual pot. In which case, rather than having salaries deposited into a single account, the salaries would be deposited into each user’s accounts before being pooled.
Having said that, Monzo haven’t ruled out enabling two cards to be linked to one account. And my ‘design’ might make keeping track of the joint account holder’s transactions tricky.
It would give users greater independence though, as if you wanted to end the joint relationship (not you of course 
maybe flatmates instead), direct debits etc. would still be linked to an individual user’s account.
I guess it’s just a question of which structure is the easiest for users to manage. Would my suggestion work for you or potentially cause issues?
Interesting, an equally good idea, I think in my case, if I had oversight and access to move funds across all 3 accounts, this would definitely work. Lets hope it comes full side!