That’s a complicated exercise, to be sure - in fact, so complex that I was compelled to compile a tutorial about how to ensure that things are locked down, in regards to unwanted involvement in Global Selling, here:
I’ve seen more than a few reports of this phenomenon over the last few years over in the NSFE (including one I read earlier today), but I have not been able to discern whether anyone has solved it w/o resort to Seller Support (and only sparingly, even then, dammit).