I would advise extreme caution when attempting to connect Thomas Isbell, husband of Discretion Howard, to that of Thomas Isbell and Temple Elliott Isbell. The paperwork is far from conclusive, especially before the early 1800s. It is extremely easy to mix up the Isbell lines, which I think is the case here.
The information on Thomas Isbell, supposedly the father of Temple Elliott Isbell, is very limited. His father is supposed to be BENJAMIN Isbell, a Revolutionary War veternan; and even here the documentary evidence is circumstantial. Benjamin migrates from Virginia and ends up in North Carolina. His oldest son, Jason Sr., ends up in Kentucky, along with his son, Jason Jr. Thomas supposedly dies around 1811 in North Carolina. Another son, Richard, will also end up in Kentucky.
I was convinced for years that my family connection to Benjamin Isbell's line was through Thomas Isbell, father of Temple Elliott, and so do some veteran Isbell researchers. Another possible candidate could be Richard Isbell, Thomas' brother. But a post by Jan Lawson (3/18/2001) shows documentation that could possibly identify my 4th grt. grandfather, Elliott Temple Isbell, as the son of Jason Isbell, Jr. I only mention this because it's easy to make assumptions. Oddly enough both Elliott Temple Isbell and Temple Elliott (born in North Carolina) BOTH end up in Jo Daviess County, Illinois. Why? Are they really father and son? Or are they following the same migratory path?
Again I would have to conclude that you are confusing Thomas Isbell with Benjamin Isbell, especially if you claim to be descended from Temple Elliott Isbell.
Of course I would urge you to take the female version of the Isbell DNA test; this matches cousins, aunts and uncles to the their male Isbell counterparts, whose DNA records are stored in a data base. Take the test and see what the SCIENCE tells you. You may find it interesting.