40 years ago, the hit show 'DYNASTY' ended it's fourth season with a mysterious woman checking into 'La Mirage' hotel in Denver, not too far from the Carringtons. The mystery woman was a beautiful, elegant, wealthy black woman named 'Dominique Devereaux', played by the Tony-winning actress Diahann Carroll, who was 49 at the time. In interviews, Carroll said she met with producer Aaron Spelling (she was a huge fan of 'Dynasty') and asked him to let her join the show and become 'the first black bitch' on a night-time soap. He liked the idea, and the two of them got to work on who her character would be.
Her character was a single mother to a 19 year old girl, and Carroll suggested she be a former secretary to Blake Carrington who had an affair with him (in the mid-60s) and got pregnant by him - she wants him to acknowledge his daughter, and let her have a share of his wealth. However, Spelling had just introduced 'Amanda' a daughter Blake never knew he had with Alexis, and didn't want to bring in another child.
They settled on Carroll being Blake's unknown half-sister, and the storyline went nowhere. Just a lot of unexplained bickering between her and Alexis (though she really had nothing to do with his former wife Alexis).
Wouldn't it have been better if they introduced her as Alexis' un-known half sister ? Maybe they shared the same father or mother ? It would have been much more interesting and explained more about their constant fighting.