I found a marriage record for William Dunn and Elizabeth Adams (May 18, 1813) with Peter Custis ad the bondsman.
William is connected (probably a brother) of the David Dunn who married Anne Custis in 1782 Craven NC.An older William Dunn died c1798 and had sons David, William, John, Hardy and Walter.I think the David Dunn who married Anne Custis are the parents of my David Dunn ancestor born 1786 NC (moved to GA c1805).Another William Dunn married Betsy West a few years later.These Dunns all seem to be related.
Anne Keady Custis and Thomas Custis are mentioned in a 1785 will for Elizabeth Aldy in Craven.I speculate that Anne Keady Custis was her sister and Thomas Custis was a brother in law.They seem to be connected and may be parents of Anne Custis (who married David Dunn)and Peter Custis.
An Anncady Custis married Rounds Munsford in 1799 in Craven.This has to be the same Anne Keady Custis which suggests her first husband was deceased.
There seems to be only one Custis family in Craven NC at that time and they must connect to VA.