Thank you all very much for your answers!
I think for my part that the
statement regarding Fw190D-9's service with 15./SG 151 might be incorrect. In the aforementioned book there is no footnote or source given, which might corroborate this story! Also it does not make any sense to equip a dedicated Ju87 nocturnal ground-attack unit with state-of the-art fighter aircraft!
@Andrew: Thanks again! When is your Air War Courland book scheduled for release? I am looking forward to it, since my late grandfather, a technican with 5./JG 54 at Cirava, told me only very little about this time.
Best
Michael