I am trying your suggestion to use a custom Shipping Address field on invoices instead of having each individual branch as customer. For single branch customers I enter the default Delivery Address and generate Delivery Notes and invoices as usual. And for multi-branch customers I leave the Delivery Address field in Customer empty and use my custom Shipping Address field on invoices instead.
I will have to enter Shipping Address every single time. And when I use copy-to feature to create a delivery note from invoice, my custom Shipping address field is not copied to the Delivery Address field. It’s a nuisance but I can live with it.
As long as it works well for generating Statements and for other accounting purposes such as correctly setting credit limit for the whole multi-branch customer rather than having incorrect credit limit for individual branch. These accounting purposes is far more important as an accounting software afterall.
Here comes another question: Why is Delivery Address available on Delivery Notes but not Invoices? As far as I know, every invoice that involves delivering products would show the Delivery Address. And it is already implemented as well. When enabling Delivery Note tab, it should be activated on Orders and Invoices in the same way it is activated on Customers.