The John H referred to by Frances would appear to have been John Herbert who in 1891 was a widower living with his widow mother at 24 Demense Road.

The John Henry and wife Edith Ann Cowell in the 1901 census do not seem to be in the 1891 census for the Island though the daughter Lily is shown as born in Douglas.

The son Henry, 7, was Robert Henry born 22 Apr 1894.
There was also John Robert born 13 Feb 1893, buried Braddan 9 Jul aged 4 months.

I cannot identify John Henry in the 1881 census.