I know this is several years after your post, but Hico is a small town that I have driven through many times. Adam's parents, Larkin Oscar and Mary Anglin Knick are buried there and I have photos of their grave markers. Let me know if I can send them to you.
My great-grandmother was Adam's older sister, Nora. She married a man named C C Bishop and they settled in Cisco, Texas. Interestingly it seemed that many in the Knick family worked in a café in Hico and then some of the children later worked in or owned their own café. C C Bishop lived with the Knicks when they first moved to Texas, worked in the same café as L O Knick, and then built his own café in Cisco. Doak and Clarence both later worked in a café in Snyder, Scurry County, Texas.