I think the James Scarffe who married Mary Callister 21 Feb 1773 Lonan will be the one bp 22 Feb 1727/28 Lonan the only son of James Scarffe & Ellinor Christian (md 23 Jun 1723 Braddan). The evidence is in Ellinor Scarffe's 1786 will that mentions her "dau-in-law Mary Scarffe" as well as making her son James Scarffe exec'r. The will also mentions her dau Mary Quill (Wm Quill md Mary Scarffe 26 Feb 1754 Lonan after she had an illegitimate child Mary by Daniel Clark).

I tentatively had placed the bee-keeper James 1803 of Raah to be this James but not 100% on this. As noted by Frances, no evidence of children of James & Mary.

The James that md Ellinor Christian was buried 16 Feb 1770 (will). He likely was born about 1700 (no Lonan registers exist before 1718), and he fits to be the "only son" of James Scarffe (ca 1670 - 1719) and Margaret Skillicorn (d 1728). The 1719 will of James says that he left his "coz Jo: Scarff house of Balla:Skarff".

My notes say that a Philip Scarff inherited Ballaskerroo in 1680 from Donald Scarff (who had inherited it in 1643 from John MacSkerff) and passed it to John Scarffe in 1700. I think one of Philip's sons will be William Scarff (ca 1665 - 1693) who is the father of John Scarff of Ballaskerroo born about 1690 & died 1742. Wm died soon after the birth of son John (and before "father" Philip) and his will mentions his "brother James Skarff". I suspect James was the guardian of his young nephew John and thus ensured the property to his "cousin" in 1719.