Copy Pietro Rotary

[Монгол]

Good time of day, ladies and gentlemen!
I beg you to aid in the identification and assessment of the picture.
   Author unknown, but dug a lot of literature found a picture in the works of Pietro Rotary.
Oil on canvas. Creation time is unknown, no signature.
   Origin stretcher missing, tinted small spots, especially on the bottom of the picture and as luck would have in the signature: ((well visible in ultrofiolete) is contaminated with fat stains.
   Size 46h38
   History painting zero-heirloom family, my great-grandmother gave my mother) was planted in 71godu: confused: the plywood and dress in the frame)
All thanks in advance, please answer if possible arguments.