Thanks for your reply, @Beebumsom .
If you wish to automatically send order information to your vendor, while limiting their access to your store, through the suggestion we discussed in this thread then yes you cannot pull live rates based on your vendor address.
With that being said, there are apps that promise to provide vendor based rates while keeping the above setup that you can explore below:
Feel free to explore some of those alternative options, and make sure to connect with the App Developers for any app-specific questions. For everything else, I’d be glad to support however I can.
Warm regards,