Bear in mind that by then Marie was 18, and Anastasia approaching 17, so they may have shared in the wine, but two bottles would anyway not go very far between several people. How many were dining that night? Are we talking about the final night they were all together in Tobolsk, or the night before everybody except Nicholas, Alexandra and Marie left? If the former, I would assume Nicholas, Alexandra, the four girls (Alexei was presumably in bed), the two tutors, Prince Vassili Dolgoruky, General Tatischev and Dr. Botkin, which makes nine definite drinkers (unless someone was teetotal), plus Marie and Anastasia. So only enough for one glass each. If we subtract the five in the first group going to Ekaterinburg, we are left with four or six drinkers, so hardly a major boozing session!
In Britain, it is entirely normal for two people going for an evening meal in a restaurant to have one bottle between them (which equates to two decent-sized glasses apiece), but you don't drive home, as that amount will put most of us over the limit.
Ann