I am going back to this bit as I need your comments on each section. This is the Ballymaglaff, ballymaglave, Belymaglach bit
James Balloo b 1645-1681 m Helenor Jamieson, James will mentions brother John of Ballymaglave, Ballymaglaff, Belymaglach(same place but the spellings I have seen) Co Down.
Comber graveyard( Co Down near Balloo): "Here lyeth the body of Alexander Agnew of Belymaglach who departed this life 29 Aug 1700 aged 52 years
Also his wife Jean McQuoid who departed this life (07) Dec 1723 aged 71 years."
So James Ballo d. 1681 has a son Alexander and has inherited the land likely.
Alexander Ballymaglaff dies 1700 aged 52 so born 1648. His brother is James of Balloo born 1645. Their father is John born at least by 1628~ roughly. . Means John Ballymaglaff was 17 when his son James was born. OK so still possible. John Ballymaglaff still alive in 1700.
Now Sir Patrick Agnew has son Sir Andrew born about 1600 and Alexander of Whitehills b before 1627. Alexander is the father of John born at least by 1628 So Alexander of Whitehills was born about 1610 say.
Now Alexander is in the 1684 curates census in Sorbie Parich at Whytthills with his successor Androw and their wives who are named. But Bk of Agnews talks about John replacing name Alex in 3 leases from Earl of Antrim after 1669 however obviously alive and well in his Tower House at Whytthills till at least 1684.John Agnew in Carrickfergus seems to have his house or hearth in 1669 and Andrew(is that the Sir or the Ship's Captain Agnew?) has 2 hearths. The politics of that century are very involved and possibly Alex couldn't legally hold land in Ireland and had to transfer it to an Irish son.
I guess that is how I see this. NowJames Balloo has a son James b 1671 that goes to America but who stays with his granda from 1681. Interesting but the curate's census would have seen the 13 year old James- but not recorded as he too young.
However I really don't see why Alexander of Belymaglach wouldn't have looked after him and his brothers as he was their cousin or indeed John of Ballymaglaff who was their uncle. As well as the three aunties.
Actually maybe Alexander Belymaglach did look after them but after 1700 they had to make their own way. He would have been 29 anyway and long left.