It is only now, when delving into this immense project, that we are able to see more clearly the confusion that occurred, and how seemingly unimportant passages can shed light on some of the most compelling questions. Yurovsky, in his note, claimed to have buried the maid with Alexei. Anna Demidova, who Yurovsky said he mistook for Alexandra, was positively identified as being in the common grave. With Olga Nicolaievna also positively identified, who out of the three remaining females would be most easily mistaken for Alexandra? The answer that immediately comes to mind is Tatiana. But before we go into the whys of this reasoning it is important to bring up the state of the bodies at the time and how this affects the ability for one to tell a middle aged woman from a young woman in her early twenties.
~Alia~

The Imperial family was killed in mid-July, when the daily temperature averaged seventy degrees Fahrenheit. Their faces had been crushed by repeated blows from rifle butts. Their hair, soaked with blood, would have dried into a black, caked, impenetrable mass. As the corpses, stripped of clothing, lay on the ground, the sex of the victims would have been obvious, but beyond that the naked bodies would have bloated to unrecognizability. Maples sometimes sees the bodies of adolescent girls, which, a few days after death, have ballooned to resemble obese middle-aged women.
~Robert K. Massie, The Romanovs: The Final Chapter~

 
With the bodies stripped of clothing, the assassins had very little to tell them who was who. We must point out though, that Anastasia's body was lacking in stature and her small frame would have been closer to Alexei's than their mother's. Tatiana was however close, if not the same height, as their mother. They had the same features and body shape, and in death, "bloated to unrecognizability" they would have been impossible to tell apart.

In order to be one hundred percent sure on the identification process, you must have all four sets of remains to compare data, but if No. 6 is Maria as is proposed here, that means we should be searching for a missing Tatiana.

It's strange, and not the answer that was expected when we first started looking into this in depth, yet now it's the only thing that makes sense to us.