You have the wrong information about Isaiah Marion "Tobe" Lawson. There are two different individuals named Isaiah Marion Lawson who both lived in Red River County. This leads to much confusion.
The first one is Isaiah Marion Lawson - b: 11 Mar 1845; d: 24 Jan 1901; m: Eliza Jane Carnes. He is the son of Isaiah Dedrick & Mary Elizabeth McCowen Lawson. (Isaiah Dedrick is my 3rd Great Grandfather.)
The second one is Isaiah Marion "Tobe" Lawson - b: 23 Apr 1868; d: 06 Jun 1954. He is the son of William Camillis & Artemetia Bankston Lawson. William Camillis Lawson is the son of Abia Lawson.
Isaiah Dedrick Lawson and Abia Lawson are brothers. I base this on DNA testing that I and a descendant of Abia have had done that are almost exact matches for 37 markers.