Cook/McDonald Photograph?

[Snohomish]

This photograph was found in an old "Cook" home about to be demolished.  I have no idea who the people are but believe they may be of the John Cook (b 1846 Glasgow, Lanark, Scotland) or Margaret McDonald (b 1850 Altoun of Loudon, Ayshire, Scotland) daughter of William & Susan (Kier) McDonald.
The picture was taken at the John Rogers, Photographers Studio, at 42 Tay Street in Dundee.  The studio seems to have been there from about 1879-1899.  Any help with information in the sailors clothing worn by the young men and the lady's fine attire would also be appreciated.