It seems that Domingo COMISSIONG came from Italy to Grenada in the late 1700's as I found the following in a textbook:
"And who cares of Domingo Comissiong the Genoan sail maker who married a woman of colour in an Anglican Church in Grenada of 1799 ?". This would make him born about 1760/1780.
Could you please send me the family tree you are mentioning (a certain Rosabelle CHOLLET of my family married a certain Jabez B COMISSIONG and they had a daughter in 1866 on Grenada).