As Donna points out, if you look through Brian Lawson's site www.lawsons.ca you will also find brothers and sisters to your grandparents.
Your grandfathers parents were married in Liverpool in 1888 at St Marys Kirkdale, an area where Mary Spencer originated. It looks like she was working on the island and returned for the marriage. The great grandparents were also married in Liverpool at St Georges Everton in 1861. James Spencer was from Manchester and Frances Weaver was from Tilston, a little place near Crewe. Crewe and Liverpool seem appropriate since this James was a railway porter.
Your grandmothers family, Frederick Callister and Ellen Louisa Howland came from Andreas, they were married there in May 1888. Ellen lived with her parents Thomas Howland and Elizabeth Goldsmith at a place called Lheakerrow near Regaby and the border with Bride. Thomas and Elizabeth both came from the parish of Bride.
Your grandparents finished their days at a cottage at Ballaseye which is the same area as Lheakerrow on the road from Ramsey to Andreas.
You can find more information in the 1881 census on line, IGI, manx notedbook, as well as that previously mentioned but ask a specific question here and many will answer.