I've located the children in census, marriage records, and death records. Still drilling down on info concerning the parents.
First off, Claiborne County, TN (birth county of Mary A Branson) is a fair distance from Roane County, TN. Seems unlikely that she would travel down to Roane County to marry. I've checked the marriage records of Roane County, TN and found no source for a marriage. What is your source that they were married in that county?
Second, you state that Thomas Cardwell was born in TN and died in an electrical storm in Indiana in 1836. What is your source for that information?
Third, What is your source for Mary Ann's parents?
If Mary Ann is indeed from Claiborne County, TN there is the possibility that Thomas is from that area as well. The marriage records for that county (pre-1850) were lost to a courthouse fire.
I'm not questioning your research. I'm just attempting to connect this family group to the correct branch. It appears that the children were all living with different families in the 1850 census. Phoebe was married in 1844 and is living with her husband. James appeared to have been wounded in the Civil War and was living in Veteran Homes post war. I've found his CW Service Records. Thomas is living with a Crooks family in 1850 in Parke County, Indiana. Do you know of a family connection to the Crooks?
I found Thomas Cardwell in the 1830 Putnam County, IN census. He is listed next to a Berry Branom (sic Branson) - Looking into Branson families in Putname/Parke Counties, Indiana now. More later.