What is your evidence for them being from Aberdeenshire?
John Christie, no wife's name stated, had the following family in Coull, Aberdeenshire
George, baptised 12 March 1819
James, baptised 30 June 1820
Robert, baptised 21 December 1821
William, baptised 17 May 1823
Archbald, baptised 1 March 1825
The listing of Archibald in the 1900 US census says he immigrated in 1845. Have you found him in the 1850 and later US censuses?
In the 1841 census, at Tillylair, Coull, are John Christie, 60; Jane Christie, 55; George Christie, 20; Robert Christie, 18; William Christie 16; and Jane Lawson, 8. A 15-year-old Archibald Christie is an apprentice merchant in Aberdeen.
In the 1851 census, at Tillylair, Coull, are Robert Christie, 29, farmer, with mother Jane Christie, 70 and niece Jane Lawson, 18. William Christie, 26, born Coull, is a lodger in Glasgow and may or may not be the same William Christie.
In 1861, at Tillylair, Coull, are Robert Christie, 38; wife Isabella Christie, 28; son John Christie, 6 months. This looks like Robert Christie and Isabella Michie (there are also two Michie lads in the household) who were married in Birse on 19 November 1858.
Robert and Isabella were still in Coull in 1871, 1881, 1891 and 1901 with varying numbers of children. Robert died in Coull in 1903, aged 80. Isabella didn't die in Coull - she may have died in hospital, possibly in Aberdeen.
It looks to me as if Robert could be the brother of the James, William and Archibald you are looking for.
Go to
www.scotlandspeople.gov.uk and invest in a few credits. Use 6 of these to view the marriage certificate of Robert Christie and Isabella Michie. It will tell you the names of Robert's parents, including his mother's maiden surname, and therefore, if I am right, the names of James', William's and Archibald's parents.
Wonder what happened to George?
Upper Tillylair
http://www.geograph.org.uk/gridref/NJ5401Nether Tillylair
http://www.geograph.org.uk/gridref/NJ5402 - it's probably this one because I think Upper Tillylair is in the parish of Aboyne