I have to say your setup is rather confusing to me.
I'm rather surprised the plumber could not add a shutoff for you very
close to where the hose bib supply line goes through the wall.

I'm glad I'm not where you are. It is about 27 here in MD, and I'm very
uncomfortable going outside.

Thanks for your post. It reminded me to shut off the valves feeding my
exterior bibs.

David