It appears that the Hugh Mackay you are referring to is the one found on this page in the website:
Clan Mackay (Bonnie Dundee and General Hugh Mackay (by Kenneth Morgan))
This was from a message posted at a forum by Mr. Kenneth Morgan who has some knowledge of European history.
This is of course a different Hugh Mackay being spoken of here than the CAPTAIN Hugh Mackay that was mentioned in the LDS records.
Two things we always have to consider when trying to establish a connection are the dates and places events happened.
Robert's will was probated on the seventh Day of October 1746.
Also, according to Dee Ann Buck who has done research on the early members of our family his children were at least all born here, possibly in Freehold, Monmouth County, NJ. These were all born during the early 1700s.
Robert obviously couldn't have been in Scotland during the 1700s because of these things.
Also, Robert was married three times. Only his 3rd wife is mentioned in his will but it is made plain that this is not the mother of his children as the codicil attached to the will indicates he made special arrangements for her care which he forgot to do when he wrote his original will.
This is the reason why we see his name being spelled in different ways throughout the will. The first part or the will itself is by his own hand and he spells his name as "Mackay". The remaining parts were put in by some court official which is why it is spelled as "McCoy".
Robert always signed his name "Mackay" with the "a" over the "c" which I believe when looking at it you can see why it became common to spell our name as "McKay". The "a" was probably accidentally overlooked.
Even his grandson Andrew spelled the name as "Mackay" as indicated in Hopewell Friends History.
Anyway, I do think that when we do go about looking for info. we need to make sure it all fits together.
Remember, children cannot be older than their parents.
Mrs. Doughtie & the late Hunter Branson McKay had a very long exchange of ideas & letters over the years about any group of Mackay....etc...
Mrs. Doughtie & H.B. McKay had exchange information about Capt. Hugh MacKay and his family members of this group appear in her book on page 390.
I have not tried to find the parish records for Capt. Hugh Mackay, but it sure appears that he was the same generation as "our" Robert MacKay.
Said Capt. Hugh Mackay, son Hugh MacKay died in Jamaica, probated his will 1763 and in GA probated in 1764. Now if we are to believe the birth date for him in L.D.S. Computer Bank, then he died at the age of 98. They have the birth year as c1665. No issue. In his will he mentioned he had a brother John MacKay still in Scotland and a brother James living in GA he died in 1786 in GA. He would have been 116 according the ages of his siblings supplied by L.D.S. computer bank.
Now said Hugh Jr. had a brother, Patrick who emigrated to GA in 1732 with Oglethrope. Using the age given by L.D.S. computer bank at the age of 64 years of age.
I will trust far more what Beatrice M. Doughtie has recorded. The children she has listed/mentioned (according to will abtracts & court records).
1. Hugh MacKay Jr. died 1763 Jamaica far more likely born c1700. Married Sarah Morgan. No issue.
2. James MacKay died 1786 GA far more likely born c1711. Not listed in the L.D.S. computer bank as a child of Hugh & Jane Mackay.
3. Patrick MacKay emigrated to GA in 1734 married in 1740 to Isabella, widow of Montague, he died 1777 GA. Far more likely born c1715.
4. John MacKay according to the will of Hugh MacKay stayed in Scotland.
So it is far more likely the children of Hugh & Jane Dunbar would be from c1700 to c1715 or the same age spread as the children of Robert MacKay Sr. of NJ/VA. Follows that Capt. Hugh MacKay more likely to be born c1679 about the same age group as Robert MacKay of NJ/VA.
Doughtie has no mention of children: Barbara MacKay, Wm. MacKay, George Mackay, Donald Mackay, Robert Mackay, Angus Mackay nor Elizabeth Mackay.
There did these additional children come from, doubt we will ever find out.