I've watched this ages ago as a youth, and always wondered where the prequel was. Now I research with the fine thing called internet and find out that was made in 1979. Now I don't feel bad for not having seen it.
Now rewatching the series, I'm so confused how is Wu Di's daughter Dugu Fang is also Wan Fei Yang's half sister? Did his wife first had relations with Wan Fei Yang's hidden dad and later marry another man and produced a daughter, thus Fei Yang's sister?