I was thinking it could be a simple implementation of how to specify pick up at the warehouse instead of at the customer’s address.
If the fallback returns the warehouse address instead of the first customer address then we know that the customer wants to pick up from the warehouse.
Like this we don’t need to modify or add any new model, just change the code that returns the fallback address.
And if the customer wants delivery at their address the delivery usage should be checked.
Or maybe this is too counter-intuitive, and even if documented will cause more trouble than it solves.
Do you think this could be the right approach?