No dates of birth are given for William Hammond senior or Mary Davidson or their son William Edward Hammond, so first thing is to track that down. DOBs are essential.
1900 Presto, Bingham, Idaho Samuel Borup 46 born Sep 1833 in Denmark to USA 1857 Mary J Borup 31 born Feb 1869 in Idaho; father born in Missouri; mother born in Oregon Lena C Borup 8 born October 1891 in Idaho Carl P Borup 5 born December 1894 in Idaho Frank G Borup 4 born May 1896 in Idaho
So...Mary J. Davidson was born February 1869 in Idaho, the daughter of William G. Davidson (b abt 1841) of Ada, Idaho (in 1880 census).
There are several William Hammonds who could be William junior’s father.
Okay, I just went and read your second post - You found Wiliam junior's death date - Good!