Nash, who has worked with Crosby in a duo format minus Stills, joined in harmoniously. “If you’ve seen us before, you know we have different jobs,” Crosby explained later. “Stills writes fantastic rock ’n’ roll. Well, he writes everything. Graham Nash’s. when I wrote ‘Teach Your Children,’ and where I was when I wrote ‘Our House.’ And it makes it more personal for them. The two-time Rock and Roll Hall…