I have put an updated Graves outline family tree at www.manxnotebook.com/famhist/families/graves.htm - I think the John James, son of Henry and Maragret Wattleworth is the father of your John husband to Margaret Bridson.

There are no immediate Graves family left associated with the Peel shipyard (those to the left of your family on my tree) - there may well be some on your line - there is reported to be a detailed tree at the Manx Museum prepared by Ruth Serjeant in the 1960's (try enquiries@mnh.gov.im)