If you check the GENFORUM message list you will find the name Mary Elizabeth Lock. She is my great grandmother and a daughter of John and Malinda Lock. That makes her and your Clara sisters. Mary was their second child and Clara was the 14th child. Much of my information came from census records and the Ancestry.com web site. There are others that have records posted on the Ancestry.com site that include the sirname Lock.
I currently have the priviledge of the possesion of my great grandparents family bible (Griffith Dickason and Mary E. Lock Dickason