Yes, as far as I can tell Mercer Bush b. ca 1796 was the s/o John Bush and Mary Polly Tillman, s/o Philip Bush and Mary Bryan.
If I am correct about this, then Mercer Bush was the nephew of Joseph Bush who died in Caswell Co., NC. ????
Which brings me back to the original question concerning the identity of those 3 Bush orphans bound to John Gately and his wife Jemima Mercer in 1788 and 1789.Jemima's brother John Mercer seemed closely acquainted with Dr. John Bush and William Bush families in Caldwell Co., KY where Jemima Mercer Gately ended up.
Why would John and Jemima take on the 3 Bush orphans if they were not related to either of them???