The 1900 census for Montana had this family that I believe was most likely the parents of Robert Roy Turk and the grandparents of Melvin Roy Turk:
Frank Turk - head. Born 1846 (53 yo) in Austria. A naturalized citizen who arrived in America in 1888 Annie Turk - wife. Born 1857 (40 yo) in Austria. Arrived in America in 1910 Frank Turk, jr. - son. Born 1886 in Austria. (The 1910 census enumerated him as b. in Montana which makes more sense!) Robert Turk - son. Born 1891 in Montana Joseph Turk - son. Born 1892 in Montana
In 1910 I could not find either Frank, senior, nor his wife, Annie. I could also not find Robert nor Joseph. Frank, junior, was in the Montana State Hospital for the Insane.
But Robert Roy Turk m. sometime between 1910 and 1916 when his son, Melvin Roy Turk, was born.
Hope this information helps someone - it is not my family.