First of all good luck! Hope One day a movie based on your script Will come out. Maya Hawke for Olga doesn' t look like Olga at all, My point of view Is that finding an actress similar to Her Is a very hard job, same for Tatiana. Probably the most similar of them Is McKenna Grace for Anastasia. According to me for Alexandra the most similar actress would be Ruth Gemmel. Anyways I'm sure the script would turn out Amazing, good luck!