Six years ago, one of the artists on http://fanart.lionking.org uploaded a picture showing an excerpt from an official Disney site that featured a somewhat..."interesting" synopsis of Simba's Pride. It said that, among other things, Zira was Scar's sister and Kovu was being trained to take over the entire animal kingdom.

Well, I had a good chuckle at that, and recently, I thought I'd try checking that site out again. I figured that after six years, it must have been taken down or changed by now.
Imagine my astonishment to find out that it hasn't. The fourth paragraph is exactly the same as it was in 2004:
[quote]It’s here that Kiara meets the mischievous Kovu, a young cub who, unbeknownst to her, is Scar’s nephew. Before his demise, Scar told his sister Zira that he wanted Kovu to be raised as his chosen successor to the throne. After Simba banished Zira, Scar’s sister-in-law Serabi and Scar’s other followers to the Outlands at the end of The Lion King, Zira dedicated herself to training Kovu for his historic role. In order to walk in Scar’s paw prints, he would need to defeat Simba and take over the animal kingdom.[/quote]
And this is site is part of http://disney.go.com/, "The Official Site for All Things Disney". I was so inspired by this "official" info that I created a family tree based on it.
Funny how fan theories tend to be much saner and logical than official statements (the directors of TLK saying that Nala is either Scar or Mufasa's cub, the head scene checker for SP saying that Nuka isn't Scar's son, etc.).