For an owner with several collection points
See each centre's day from where you are — read only, and honest about what that means.
You add an operator by their phone number. They get an accept-or-decline prompt on their own phone — nothing is linked behind anyone's back, and there is no invite code to leak.
Once linked, you see each centre's day: litres, amount, member count, and their full lists of entries, members and payments.
Be clear what this is. Your view is read only. Each operator runs a full account of their own, not a branch inside yours, and nothing you do writes back into their data. If you need to change something at a centre, the operator changes it.
You can require an operator to take quality readings from the machine rather than typing them by hand, which removes the manual escape at that centre.