I wonder if Wm came back to marry on Island - I can't see him or family in 1861 census so possibly the family did emigrate early that year - a number of emigrants did return around this period and up to WW1 to marry Manx - if I'm correct with identification his gmother + some cousins remained on Island so there might well have been communication between families - there might be some mention in the press - again try www.imuseum.im tho you need buy a newspaper sub