The genealogy for the McGuinness line comes from McFirbis while the other three lines are listed in Laud 620. Both the O'Hatty and McGuinness genealogies match up well with names and dates listed in Irish annals. The identity of the two right-most royal lines is uncertain. The line that begins with "Gairbhidh" may have led to a sept with him as its namesake. The identity of the other "?" line is unknown, except to venture that it could be the O'Coinne/O'Kenny/O'Quinn or O'hAinbhith/O'Hanvey septs that O'Dugan mentions as "anciently powerful" along with the O'Gairbhiths. However, oddly enough Rawlinson B 502 (p. 184) lists a nearly identical line of descent for the genealogy of the Uachtair Tire. The genealogies are identical up to Ailill and Feidilmid, but rather than continuing with Mael Cothaid the Uachtair Tire genealogy continues with a Fiachrach Cassain to Colla da Crioch. (And Rawlinson B 502 does not list this same "?" collateral line in the Eathach Coba genealogies). Uachtair Tire is described in Onomasticon Goedelicum "as west of the inner bay of Dundrum", which would place it somewhere just north of Castlewellan in Iveagh.

There is an complication regarding the Gairbhith listed in the genealogies and the Gairbhith mentioned in the annals. The Gairbhith in the genealogy had a brother Cummasach who the annals describe as having lived in the first half of the 900's. That would mean that the Gairbhith listed in the genealogy would have lived two or three generations too early to be the Gairbhith who died in 1004 AD. Perhaps there was an error in the genealogies, or the Gairbhith who died at Crewe Hill may have been a grandosn of the Gairbhith in the genealogy. (Or equally, the Crewe Hill Gairbhith may have been of another Iveagh royal line entirely).

Irish annalists were not always careful to distinguish between entries relating to Ui Eathach in Co Down and a similarly named area/group in Co Armagh. Therefore there may be some kings in the annals listed above that do not actually refer to kings Eathach Coba. One suspicious entry is the final entry regarding Ruadri O'hAilellain, since that surname is not associated with any other known Iveagh royal lines.