...can you do what I just did and contact their support to request that they add the Dallas box sets to their library?
I was on a flight recently that had the original series 3 box set as part of the in flight entertainment and I watched loads of episodes when I should have been sleeping ... they were magic. JRs one liners were brilliant. The series I saw Miss Ellie had a mastectomy as part of the story line. I believe she won awards for that storyline being informative and encouraging people to self check (this was ground breaking in the late 70s).
I contacted Netflix support (live chat) and they consider requests from customers. The person on the other end was very helpful and informative and said that the do look at requests from customers, so you never know.