As I mentioned earlier, this feature isn’t designed to be or replace a joint account. It’s meant for small uses: a gift for a friend’s birthday or a colleague’s leaving, for a shared household’s bills, or for saving up for a trip with friends, and everything in between.
Also, the intent of this feature is to share a pot with trusted friends or roommates (you know where they live if the pot’s owner was to run with the money 
), and, although you’ll certainly be able to, it’s not meant for sharing large or any sum over a long period of time.
We certainly want to minimize the bus factor. That’s why we’re designing this feature so that the owner of a shared pot will be able to give withdrawal permissions (full or partial) to any person with whom the pot is shared with.
Just to be clear, no, pots and shared pots are not current accounts on their own, therefore aren’t eligible for overdrafts.