I have some Grigori Rozanov headcanons:
In the book, Alexei and Ilya are supposed to be full siblings, with Alexei four years older. So Alexei born in 1987, and Ilya in 1991. Alexei before the fall of Conmunism, Ilya when the Soviet Union was crumbling. He was canonically born June 1991, and the Soviet Union ceased to exist that same December. Grigori was in his mid-forties when he married Irina and had Alexei, either 50 or very nearly 50 when their younger child was born.
Anyway, what if Grigori was married before Irina, but his first wife couldn’t have children? An old-fashioned guy like Grigori wouldn’t have waited until he was in his mid forties to marry for the first time. Especially in a homophobic society where being a “confirmed bachelor” would be considered suspicious.
Grigori was clearly a high-ranking, influential guy. He would’ve needed a wife, if only to cook, clean and host parties for him. But there’s no mention of older half-siblings who also want a cut of Ilya’s hockey riches.
Maybe Grigori’s first wife was the daughter of an influential Party member and he couldn’t divorce her for being “barren”. His father in law would’ve torched his career in revenge. So he stayed with her until she died of natural causes. Or she finally got sick of Grigori and divorced him.
Then he remarried the much younger Irina, who could get pregnant, unlike his first wife. Which would explain why there’s no mention of a first wife and Ilya’s much older half siblings with their hands out like Alexei. Either she divorced Grigori or she died, and ceased to be relevant. Since she hadn’t fulfilled her wifely duty of giving him children.
Grigori remarried to Polina after Irina’s suicide. It’s never stated exactly how old Polina is, but probably closer to the age of her stepchildren than to the age of her husband.