Benjamin Coakley did not die or go missing in 1787. He separated from his wife, Sarah Rebow (Ribaud/Ribou/Rebo) via a separation contract filed with the State of North Carolina in 1786.
Sarah married William Hawley in 1786 -- raising young Henry Coakley (born 1784 on Anguilla) and his step-sister, Ruth Hawley (later Ruth Hawley Eulls).
Benjamin continued to work/live in the Princeton, NC area -- his letters feature in the John Gray Blount Papers books, Vol 1-4 -- (free PDF downloads I highly recommend reading.). He marries Milly, widow of Abner Neale and, upon her passing, marries Sophy Hall, in 1813. Benjamin Coakley passed away in Washington, NC in 1816.
Henry Coakley purchased 1/3 of the Browns Bay estate from a Brown relative, acquired 1/3 through marriage with a niece of the Brown family (Hester Brown -- who was also his first cousin), and received the last 1/3 via inheritance from his aunt -- Mary Coakley Brown (known as "Big Ma").
Henry had four children with his first wife, Eliza Woods -- George Washington Coakley, Letitia , Mary Rebecca , Eliza-Julianna, and Henrianna. Henry wished his children to move to the US and his will requested they go to his half-sister, Ruth Hawley Eulls.
Henrianna remained on St John until 1841 and I've found no further info on her beyond that she remained with her step-mother, Catherine, and 5-year-old step sister, Amanda Malvina Coaklay. All are reported leaving St John for Great Thatch Island in October 1841. No further mention of them on St John.
George Washington Coakley was already in the US. His three sisters (Letitia, Mary, and Eliza) arrived in Philadelphia in May 1837. Unknown if any returned to St Croix during their lives but the three who arrived in the US all passed away in the US in the late 1800s/early 1900s.