The oldest known Philemon Childers is said to have been the son of the oldest known Abraham/Abram Childers. Philemon is shown on a large Childers document to have been the brother of Abraham Childers "Junior" and his wife Ann Pew. Abraham and Ann (Pew) Childers are said to have had: Abraham "III," Henry, Robert, Philemon (a younger one), John and Jane. Abraham "III" and his first wife Elizabeth Cannon had several children, including an Elizabeth who married James Thomas. Abraham "III" was married two more times, and his third wife was the widow Lucy (Thomas) Nevil. I don't have proof of the relationship between this Lucy Thomas and the above James Thomas, but I think I read that James might have been her son (maybe born out of wedlock, since Thomas seems to have been Lucy's maiden name; not sure about that story).
The oldest Philemon (known as "Lemon") and his wife Mary (maybe Mary Howard, daughter of John Howard, per one source) had: unknown daughter, Thomas (who had a Thomas Junior), Abraham, Philemon (yet another/third one) and Mary. There was a Tabitha Childers born into this line later (daughter of the "third" Philemon, I believe), and the above Abraham "III" and his first wife Elizabeth Cannon also had a daughter named Tabitha Childers (who was my 5th ggm; these two Tabitha Childers should not be confused)
There was a Philemon Childers who was imported into Charles City Co., VA (CCCo) in 27 Oct 1673 by a John Maies (for which Mr. Maies received some land). I suspect that this was Philemon "Lemon" Childers, but I have no proof of that. There was also a record in the 1690s that mentioned some land in CCCo that Philemon Childers had assigned to Thomas Cook, Jr. Finally, there are some records on a Thomas Childers/Childres in CCCo in 1755 and 1770.
Because there was a Philemon Davidson who died in CCCo in 1773, I wonder if Philemon Childers had a daughter in CCCo who married a Davidson (perhaps unknown by researchers). The daughter of Abraham Childers "III" and Elizabeth Cannon named Tabitha Childers married my 5th ggf, Hezekiah Davidson, and they had a son named Philemon Davidson (died in 1810 in Cumberland Co., VA). I do not know if this Philemon Davidson was named for one of the several Philemon Childers in Tabitha's family mentioned above, or if he was named for the earlier Philemon Davidson in CCCo (or a little of both, perhaps).
I have not been able to prove if my Hezekiah Davidson was out of the Davidson family that was in CCCo. My first record of Hezekiah was in Albemarle Co., VA in the 1740s. He moved to Cumberland Co., VA by 1760, and he died there in 1793. After Hezekiah died, Tabitha (Childers) Davidson remarried to a Gabriel Bradstreet Peaseley, and they had a few children together, including a Lucy Peaseley. Lucy Peaseley later married Reuben F. Davidson, my 3rd ggf (and a son of my 4th ggf, Philemon Davidson (died 1810), and his wife Mary). As such, it appears that Reuben F. Davidson married the daughter of his own grandmother! Just to complicate things a little more, after Tabitha died, Gabriel B. Peaseley remarried to Judith Davidson, another child of Philemon and Mary Davidson. As such, Gabriel B. Peaseley married the granddaughter of his former wife Tabitha!
I have some more on the Childers if you are interested.