In our club, we have a designated tank level, and a designated place, or range you can refill at. So, it needs to be full, or it needs to be short by the distance of the designated place. If it's any less than that, you owe the next member money when they fill it and determine how much that is.
Plane has to always be returned full or that much short. So, that's one of the downsides of shared ownership, you just have to calculate that last fuel stop into any trip before pulling in for the day, just part of the deal.
How it gets the correct level in it is up to the member, so maybe you do cans, maybe your partner makes a last fuel stop. But, I wouldn't micromanage that part of it, cause the day will come when it's short fuel, and the cans are empty, and now you're angry...
It can end up being a real point of contention, and I have found the best way to handle it is what I stated above (plane must always be hangared after any flight at X fuel level), and to address it right away if it comes up short, otherwise it encourages slouchiness and pretty soon other things start coming up.
Bring in the old saw about "Who would want 2 spouses, when 1 is trouble enough...". Your spouse is one spouse, the airplane is another, and now you have another one with your co-owner
Do you already get in arguments about who drove the car last without putting gas in it?