I have someone who has 2 portable generators and a main panel for the house and a sub panel for an inlaw addition.They want a reliance 6 circuit manual transfer switch installed for the main panel (gen.#1)and a second manual transfer switch for the sub panel(gen#2). Each manual switch requires a 30 amp power inlet mounted outside.These switches only do 6 branch circuits , not the entire panel.My concern is with the sub panel neutral. Any thoughts?