i agree there is capitalization in the Marriage source image.
I have added Frank Fountain-714 as father of Jessie since he is the 'profile' that is linked to his mother. I added the 'La Fountain' as an Other Last Name.
I found 1870 census in Plattsburgh, NY for Frank and 'Ellen' / Helen, living with Frank's parents, siblings, and paternal grandparents.
It looks like his father, Joseph Quintal-126, changed his name, as did one other sibling, to his mother Marian's 2nd husband, Jean-Baptiste Fontaine, at some time. Information is in profile of this person in the 'Bio from a New York ancestor', stating he used Fontaine. These are the grandparents in the 1870 census. I have added that information to Joseph's profile, also.
1850, 1860, and 1880 Census for his parents Joseph and Julia have Fountain, only the 1870 had 'La Fountain'. The 1880 census family list looks like Emma, Frank and Helene's oldest child, may be
Based on that information, it looks like Fountain was used as the 'family' name most of the time, and definitely at the time of his birth. The other problem is that Frank's name in 1850, 1860 and 1870 census is different, ie Leon, Levi and Frank, based on the age of that child.