[Mercat]

I thought that they had killed them all.

[NRx]

They killed the immediate family and a large number of the extended. But some escaped.

[Harmless Teddy Bear]

Not hardly. There were too many to kill them all. A number got away including the niece of the Tsar, Princess Irina Alexandrovna.

Russia had over a million Prince and Princesses.

Unlike the British royalty where the only people who can pass the title of prince and princess to their children is the Monarch in Russia the title was handed down to every legitimate offspring who then passed it on to their offspring.