Hi Andrej
maybe you are on not right site. Better when you go to Finnish Air Force site or other one where people from Sweden can answer, then on this one.

In Sweden if it was its plane, this case shold be very exactly written and the note to Soviet ambassy also should be submited.

In Russia maybe only Miroslav Morozov could add some fresh data if he wants to do this cocnerning VVS KBF site. No other info like exact MBR-2 unit is know even in this small run books (Protiv Finlandii - VVS KBF in Winter War)

Regards
MirekW