These are the Imperial survivor statistics, copied from the sticky at the top of The Question of Survivors board:
Olga: 28 claimants
Tatiana: 33 claimants
Maria: 53 claimants
Anastasia: 33 claimants
Alexei: 81 claimants
Total: 228 "imperial children" who survived the Ekaterinburg massacre
It just goes to show how misinformed everyone is on this thread. Alexei was actually the most popular among claimants, getting almost triple the amount of impostors using his name as his sister Anastasia. Maria came next, with Anastasia and Tatiana sharing third position. Olga is not too far behind.
So really, there weren't 'so many' Anastasias. In general, if people wanted to pretend to be a member of the IF, I suppose they just chose the one that either most appealed to them or the one they thought they could most convincingly resemble. It's nothing to do with Anastasia being the least visible/most childish/most likely to have changed appearance, because she wasn't the most popular choice of claimants anyway.
I would imagine it was a case of, 'I'm short...I'll have to choose Anastasia', or 'I have a wide forehead...I'll have to choose Olga'. Picking the GD with the most similiarities to yourself would give you more likelihood of success. It's common sense really.
Alexei was the most popular because he was the heir and the one who could inherit the 'fortune' and the 'throne', etc. The majority of Russian people probably were either not aware Alexei had haemophilia (it was not widely advertised, though it was made public in around 1910 I believe) or did not know what it meant, therefore for contemporary (as in of the time, not of today) impostors would probably have not taken the haemophilia into account.
As far as I know, there have been claimants to be Nicholas and Alexandra, but I couldn't name specifics. If there's a possible fortune to be had, it's surprising what stories crazy people can concoct.
And as for this 'Anastasia was the most likely to have changed facially' theory, that's complete nonsense.
Who can look back at their photos of being a toddler and recognise their facial features in that child? The vast majority of people. If you look at photos of a five year old, ten year old, twelve year old Anastasia, etc, you can see clearly the 17 year old she became. From the age of 17 she was not going to have her facial structure and features fundamentally changed beyound recognition. That's like saying a woman of thirty is unrecognisable from her same self as a teenager. How come my mum, at 52, still gets stopped in our home town by people she went to school with aged 10? People really don't change that much over the years. They just look older versions of their younger selves.
Rachel
xx