I'm working on a proper familytree but it'll take some time before it's finished.Yes, I believe Scar is Kovu's father, no matter what they say in the movie.
Yes, Thando and Xolo are half-siblings. They wanted to keep their bloodline "pure".
Mohatu, Thando (the selfish lion), Ahadi, Uru, Mufasa, Scar, Sarabi, Sarafina, Aheri, Simba, Nala, Zira, Nuka, Vitani, Kovu, Kiara and Kopa (c) Disney
Mosi, Nzuri, Mbaya, Xolo, Asali, Safura, Sifa, Shaka, Hasara, Jamili, Zingela, Thema, Jasiri (c) Nadra

Lol, Zira's just like "Hey baby" and Scar's like "Gahh!" while Nuka's hanging on for dear life XD Awesome picture ^^