I'm sure you have seen the info below many times. I copied it from an e-mail of Mac Elliott's. My connection is with Joseph Hickman, whose daughters married Henderson brothers. I have often wondered if Thomas Hickman, below, would be related to my Joseph Hickman, also below, possibly a brother or cousin, since they both owned land on Sinking Creek. I've seen a website showing my Joseph served in the TN Light Horse Infantry during the Revolution but have never seen any proof, and the timing is off, unless he lived there twice instead of the once I know of (moving back and forth from NC more often than I know of).
Another point: My Hickmans lived near Isbells in Surry Co., NC (now Yadkin Co.) Their were other Hickmans in the area as well, including the families of a John Hickman, who may have been my Joseph's brother. I believe some of those Hickmans married into the Isbell family (one NC descendent of these families had the name of Isbell Hickman).
And, did your Isbells perhaps spend time in MD, where my Hickmans were at some point before moving to NC>TN>NC? Many say we are descended from the PA Quaker Hickmans.