darklordoftech said:

Going only by Star Wars, do we know whether whether Owen was Annikin's brother, Beru was Annikin's sister, or if Lars was the maiden name of Luke's mother? Was Owen actually intended to be Obi-Wan's brother in 1983 like Obi-Wan says he is in the ROTJ screenplay and novelization or did Lucas drop that idea by the time ROTJ was released? Would Owen being Obi-Wan's brother preclude Beru from being Anakin's sister or Luke's mother's sister?

Also, I'd love to read the first edition of A Guide to the Star Wars Universe because it wouldn't be polluted by the EU.

Well, all of the info I've provided so far (except for some on Mon Mothma) is from Lucasfilm, and not the EU. Most of the entries are divided into two sections; the Lucasfilm section (including the films, novelizations, and the radio dramas) and a Licensed SW section including all EU elements of a character, place, etc.

(Of course this doesn't help us figure out when stuff was retconned by Lucas in between the making of the three films. The book does for example specify that Owen is Obi-Wan's brother because that was the official Lucasfilm canon at the time since it made it into the novelization.)