The character most strongly fictionalized is 'Uncle Leo.' I made him up. In real life, there was instead a good-hearted half-brother. He was seventeen years older and shared a father with Olga and her siblings, but had a different mother. (I presume the first wife of my grandfather died in childbirth - a much too common occurrence in those years.) So the 'real' savior of the younger children in Siberian exile was not a communist supporter.
As a novelist, however, I make no apologies for creating 'Uncle Leo.' I wanted to show how nobody could be trusted in those years. Bad guys are so much fun to create - and a book full of victims could become uninteresting. Also, as someone recently pointed out, Stalin can't be blamed for all the deaths in the Soviet Union. He couldn't have done it without help - and there were plenty of people like my fictionalized 'Uncle Leo' who were only too happy to improve their lot at the expense of others. This is true in every society. The exploited become the exploiters.
What remains true, though, is that millions of kulak families lost their homes, many their lives, and all suffered untold hardships, when the Soviet Union switched to collective farming in their first Five Year Plan.