Violet Dumphey married John William Callow at Kirk Braddan 20 Dec 1900.
JWC was born cir 1875 VD was born in 1800 in Cronkbourne Village.
VD's parents were Nicholas Dumphey born cir 1855 in Ireland and Minnie McLean born cir 1853 in Scotland.
ND and MC were married in Braddan 9 Sept 1879.
VD was the eldest of three daughters, her sisters (all three born in Braddan) were Lillie Lucetta (born cir 1882) and Minnie Miranda (born cir 1887)
JWC and VD had four sons that I'm aware of although lately I have heard that there may have been other sons and a daughter (presumably your Grandmother) The sons that I'm aware of are: William Callow born cir 1912; Benjamin Callow born 31 March 1914; Robert Callow and George Callow. It appears that Robert and George may not be Violet's sons since Violet died April 1914 (if family tradition is to be believed she died giving birth to Benjamin.)
It appears that after Violet's death JWC took up with Violet's sister Minnie; certainly Minnie was part of the family up until her death in 1965. Again family tradition is that they married but I have found no evidence for that.

If you try searching the 1901 census you'll see that Violet was married (and listed as a Callow) but at her parent's home. John William was working as a fireman onboard the manx steamer "Prince William" and is listed in the census at Liverpool. You will find Violet in earlier census's but as yet I've been unable to find any more on John William.

JWC's mother is currently unknown, his father was William Callow

My wife is Benjamin Callow's grand-daughter.

If you'd like to discuss this further or have any extra info you can email me at richard_knight at hotmail.com