Frances, thank you. This helps a lot. I had the two families muddled. Also, I see Wm Kneale & Jane Gelling married in Braddan 1773, which fits well. Jane's parents lived there, and the date fits better than the Oct 1777 marriage contract date.
Now I'm puzzled about what this marriage contract is all about. If I have my facts right, the groom's father Daniel Kneale "of Graw" died in 1774 and the other parents were still alive.
A review of wills would help greatly with all this.