Public App for Seller Partner to use Amazon Multi-Channel Fulfillment

Hi,

I am developing a public app to facilitate businesses using e-commerce selling platforms to use Amazon MCF to fulfill their orders.

I have a question about the necessary authorization needed. If a business has a Seller account in North America by authorizing my app in North America can they fulfill orders that will be shipped to countries outside this region or they need to authorize my app in other regions to do that?

Should I show Authorization buttons for all regions and let seller select the region his Seller account is in?

Thanks