Have you checked thoroughly into William Creech (sometimes written as Williams and sometimes as Creach) of Dickson Co., Tennessee? He was b.ca 1796 NC. Per his 1840 census in Dickson County, he had males in his household older than show on the 1850 census; perhaps one is John b.ca 1830 TN.
Louisa Cathey/Cathy would have been about 18 years old in 1840 (she was 28 yrs in 1850) so she might have been working outside the household and not counted on the 1840 Creech census. She and at least two of her daughters that I can identify are scattered about on the 1860 census; did she die or remarry after 1860?
William Creech was old enough to have been Louisa's father. His wife of 1850 would be a squeeze to be Louisa's mother but she not have always been the same wife. However, you don't seem sure that Martin and Louisa are your ancestors so perhaps more work is needed before this point?