Hello Viv,
Margaret Quayle has adopted 2 Chilldren, in the 1911 Census, William Cowin and Earnest Mc Clean, could these be her Daughter, Catherine's children ?

1901 Census, Isle of Man, Patrick, Foxdale.
Lower Foxdale Road.
Margaret Quayle Head M 55 Living on Own Means Isle of Man Patrick
Cathrine Quayle Daur S 30 Boarding House Keeper Own Account Isle of Man Patrick
William Cowin Boarder S 13 Isle of Man Douglas
Earnest Mc Clean Boarder 4 Isle of Man Lonan
Ivy Cretney Boarder 1 Isle of Man Marown
Charlotte Murphy Boarder S 34 Isle of Man Michael

1911 Census
Hamilton Terrace, Foxdale, Isle of Man
Margaret Jane Quayle Head 65 Married, Patrick IOM
Catherine Ann Quayle Daughter 40 Single Patrick IOM
William Quayle Cowin Adopted Son 23 Single Miners Labourer Lead Mine Douglas IOM
Ernest Mc Clean Adopted Son 14 Single Tailor's Apprentice Laxey IOM
Charlotte Murphy Lodger 44 Single Michael IOM (Feeble minded)