I believe calgary17 covered all your questions for me.Hello canvan14 - Thank you for the replies.
For
#1 we did not include him in an "interest to sponsor form" do you know what number IMM form that is?
#2 We will check over the form and resubmit so my wife can check on her mother's file.
#3 We thought that each had to have their own form. We will put her entire family on one form but it states "Each individual must sign their own
copy of this form by hand." That would make me think they each need a separate IMM5406 as we had submitted one with all them on one sheet already?
A lot of people made mistakes on the interest to sponsor form. But now you are aware of a crucial information that your FIL must be included in the application and therefore counted toward the family size.
For your MIL case, your FIL is her only dependant. Keep that in mind and go from there.
As for #3 you just need to have your father in law fill out his own form as well since he is considered as your mother in law's dependant. This form again must have all information that are included in your MIL's form (apart from his own parents and siblings' names)