Tessier Family Genealogy Forum
Don't know if you did get a chance to look at PRDH online at www.genealogie.umontreal.ca.
But when I plugged in your names, there's a slew of info waiting for you, especially when plugging in "Amable" "Custo". If you have access to the actual series of books, you shouldn't have any problem tracing both families through the marriage and baptism records at Lachine and Montreal. If not, let us know, as there are a number of people on the forum who can help.