I know most Russian experts believed the "missing daughter" (whose fragmentary remains have since been discovered, along with Alexei's) was Grand Duchess Maria. However, English and American geneticists and other scientists who examined the remains state that the "missing" daughter was Anastasia, not Maria. Based on the evidence I've read--and no, I'm no expert--I think the missing daughter was Anastasia. (My opinion, BTW, has absolutely nothing to do with the fact that I'm American. I just felt that the Anglo-American team had better evidence to support their conclusion that it was Anastasia who was missing.)
In the end I guess it really doesn't matter. Even if Alexei and Anastasia were found separately from the rest of their family, the sad fact remains that not a single member of Nicholas II's immediate family (his wife and children) survived. They all died--were murdered, more accurately--together in that wretched basement in the Ipatiev House in Ekaterinburg, Russia, along with several devoted servants. Tonight marks the 97th anniversary of those bloody and heartless executions. Hard to believe it all happened so long ago--it breaks my heart knowing that those five beautiful children never got the chance to live out their lives. May they rest in peace.