Old brother marries younger brother Fiancée. Irate younger brother take off on his Harley
Old brother marries younger brother Fiancée. Irate younger brother take off on his Harley
Back Home Again by woodmanone? I think there is at least one other that fits the description. I'll keep looking.
Good Hunting, limab
Third Time's the Charm by Xalir
https://storiesonline.net/s/15520/third-times-the-charm
https://storiesonline.net/a/Xalir
Third Time's the Charm by Xalir
Technically, this is a case of a younger brother getting the middle brother's girlfriend, with parental approval.
Not Fiancee's sister, but wife's little sister. By Charlie for Now.
https://storiesonline.net/s/18067/colin-and-colleen
https://storiesonline.net/s/63339/heirloom
Similar but not the same. Younger brother is in love with his brother's fiance and leaves.