This website and the series is wrong when it comes to the Petrov bloodline name. Since they write it as Petrova when it is actually Petrov ( notice the 'a'). This is due to the addition of the letter 'a' in many Slavik countries. Nina Dobrev is actually Dobvera, but she changed it so there is no confussion. The reason I know this is because I am Slavik exactly the same thing happens to my last name. Second Nina Dobrevs real name in her language has the a at the end (I'm Russian I can read it).
On another note I love this show!!!! More, there are so many connections between me and Dobrev! She was born in the city Sofia,Bulgaria, this is a silly connection but my name is Sofia, she was raisend in Toronto and immigrated to Canada, I immigrated to Canada and am in fact living in Toronto. :)