Further to the posting on the Adair WILL board re William Adair, of Rath, Queen's County, Ireland, will 1774 -

In Burke's Landed Gentry, 1852 edition under Adair of Bellegrove there is mention of the Adairs of Rath, Queen's co.

I will start with Robert Adair (brother of Bishop Archibald Adair) who was father of -
Archibald Adaire who m. Mary, dau. of Sir R. Campbell, and had a son Thomas Adaire, b. 1641. Both Thomas and his father Archibald served under King William III at the battle of the Boyne in 1690 (Archibald would have been about 70yrs ?).
Thomas Adaire b. 1641 married Mary, a dau. of the noble house of Hamilton in Scotland and settled in Queen's County.
(Note that it does not say that she was Mary Hamilton, but "of the noble house of Hamilton").
Thomas and Mary had issue:
Archibald
William
John
Robert
and a large family.

Archibald Adaire m. 1731 (would he or his father have been quite mature when they married ?) Jane Chateneuf.

Archibald and Jane Adaire had issue :
1. John
2. Mark Antony d. young
3 Mary d. unm.

John Adair of Rath, Queen's County m. 26 Feb. 1776 Rebecca Maquay of Dublin. John Adair d. 14 July 1809.
John and Rebecca Adair had issue :

1. George Adair b. 13 Sep. 1784 m. 16 May 1822 Elizabeth Trench/French dau. of Dean of Kildare.
2. John Adair b. 3 Jan 1792 d. 3 Jan 1839
3. Elizabeth
4. Jane Adair m. F.W. Fortescue of Miltown Grange, co. Louth.
5. Mary
6. Sarah
7. Charlotte

The eldest son, George (d. 14 July 1809), and his wife Elizabeth (d. 21 March 1823) of Bellegrove ( Ballybrittas, nr. Portarlington) and Rath, Queen's County, Ireland, had an only son :

John George Adair b. 3 March 1823, magistrate and deputy-lieut. for Queen's co, and high-sheriff in 1822.
(Did he build house at Donegal and send the tenants to Australia and America ?)

This lineage is a little confusing to me as other lineages noted that Bishop Archibald Adair was brother of William Adair of Kinhilt and son of Ninian Adair.
However, Playfair's 1811 lineage gives Bishop Archibald Adair as son of William Adair and grandson of Ninian, the same as this Bellegrove lineage.

If we put them with the East Suffolk lineage in Suckling's book of 1846, then Archibald Adair ( son of Sir Robert Adair who m. Jane Edmonstone ) was also shown to have been of Litter in Queen's County who died Sep. 9, 1692. He would then have possibly been the the Battle of the Boyne with his son Thomas. Suckling's book only shows a son William Adair of Litter who d. 15 April 1712 who m. Thomas L'Estrange of Moystown in King's Co. However, that is not to say that either Thomas or William were the only sons of Archibald Adair of Litter.

Calling on our brainy Adair folk to sort this out.