Many thanks for the quick reply! All understood and seriously looking forward a multi-channel / cloud service.
Re: "1. you can edit the order and pick a different inventory already."
I can see now how that works. One issue - when an order changes from "pending payment" to "processing" it triggers the order confirmation email to the client. Only workaround is to go straight to "completed" and trigger the completion email instead. Not ideal, but I can see that you're using the standard Woo process here so not sure what can be done about it.
Re "2. you can do that too when you edit the order simply add one more inventory and reduce the other." Sorry, I meant to split an order to fulfil separately (eg if 1 item is out of stock, but the others are ready to ship). I can see that's not part of your plugin, I will check out "split order" solutions separately.