Below you will find information I have acquired about the family(ies) in these posts. You requested information on the John and James Holmes who were merchants. I believe these are the same and related families (albeit they are incomplete)
Francis Joy was the father of Henry Joy, Robert Joy and Ann Joy. Ann Joy was married to Henry Joy McCracken. The brother of Ann Joy, Henry Joy was married to Mary Isabella Holmes, the daughter of John Holmes (born 1745 in Belfast and died 1825) and Miss Patterson who died before 1825.
John Holmes (birth abt 1709-died 1777 to 1779) and Mary Wilson (1714-1779) were the parents of the above John Holmes born 1745 in Belfast.
John Holmes and Mary Willson (1714-1779) had the following children:
John Holmes born about 1745 who was married to Patterson
Mary Holmes born about 1747
John Holmes and Miss Patterson had the following children:
1) Mary Isabella Holmes who married Henry Joy (son of Francis Joy). Their children were: Robert Joy, William Briece Joy, Henry Holmes Joy, a daughter who married Mr. Tomb and a daughter who married Mr Holmes in April 1784 at Belfast, Antrim, Ireland.
2) Jennet Holmes born 1774 in ,Antrim, Ireland who married William Russell of Edenderry, Down, Ireland
3) Elizabeth Holmes born 1775 in ,Antrim, Ireland who married John Holmes Houston born about 1767, the son of Thomas Houston of Dublin, Ireland and Mary Holmes born about 1747 of Belfast, Antrim, Ireland, the daughter of John Holmes and Mary Willson.
4) James Holmes born about 1777
5) John Holmes born in ,Antrim, Ireland who married Ann Daniell or Agnew - am not sure - just got this information- I may be reading something inaccurately - and this couple had children: Ann Holmes and Isabella Holmes.
6) Henry Holmes born 1778 in ,Antrim, Ireland
7) Catherine Helen Holmes born 1780 in ,Antrim, Ireland; married 20 Feb 1801 at ,Antrim, Ireland to John Russell of Newforge, Ireland. This couple had a daughter, Isabella Russell born 1802 in , Antrim, Ireland who married William McCance born about 1800 - Marriage was 30 April 1824 at the Belfast Presbyterian Church, Belfast, Antrim, Ireland.
Admittedly, most of this information is rather sketchy and incomplete. Would appreciate documented additions. I would like to know where fits Eleanor Holmes, the witness in the McCracken case. I can document this information albeit it is not generally primary information. If interested please write me at ljmasters at xmission dot com.
Hopefully I have transcribed the data correctly. Please, if interested, contact me.
An interesting book, "The Linen House of the Lagan Valley: The Story of Their Families" includes a photograph of a Holmes home. From that book, it is learned that in early 19th Century Belfast, there were a nunmber of wealthy families e.g. the Charles, the Russells, the Holmes, the Joys, the Hunters, etc.
Further it is learned: Newforge was the site of an ironwork established around 1630. It was about two miles from Belfast on the river Lagan. In the mid-1700's a bleach green had been established and in 1784, John Russell of Edenderry bought the bleach green at Newforge. Possibly he built the new house around 1790 for his second son, John who married in 1801 to Katherine Helen, daughter of John Holmes, a Belfast banker. His brother, William Russell had married Jennet Holmes, a sister of Katherine Helen. This brother William Holmes inherited Edenderry House and the bleach green upon the demise of his father in 1803.
There is an entire chapter in the above named book on the McCance family who were intermarried with the Holmes