From the bit you gave this seems to fit for the family, except for Lenny, and there is a birth record for a Leonard Burns in 1912 Liverpool which is probably him.If this is the right family let me know please.
1911 ABERCROMBY, LIVERPOOL, LANCASHIRE, ENGLAND 51 CORNWALLIS ST. BURNS
Alfred, age 34, dock labourer, born Liverpool, married 13 years
Elizabeth, age 30, wife, born Liverpool, married 13 years
Wilfred, age 4, son, born Liverpool
Frederick, age 2, son, born Liverpool
Lillian, age 12, daughter, at school, born Liverpool
If this is the right family do you know about what year Wilf and Fred left for Canada?The Canadian passenger lists database goes to 1935. I did not find either of them listed.