Today there is a Customer Setting (Direct Invoice) to setup if a customer get's an Direct Invoice out of an (return) order posting or if he get's a Combine Shipment. Additional there is a confirmation dialog at every order posting if this order should be invoiced or/and shipped/received. That's a little bit double and this both setups should be merged. Also a wrong decision at the confirmation dialog has a big impact (at worst an invoice correction).

I think it would be bether if there are special actions in the menubar to post an Shipment/Return Receipt and an Invoice instead of the confirmation dialog so that it should be possible to deactivate this functions for some users (for example the order processor has to create orders and maybe post them, but never invoice). Also there should be the possibility to automatically post the (return) order following the direct invoice-flag, so that depending on the Direct Invoice-Flag the invoice is created or not (and the people how post the order has not to decide).