Family members

Hi everybody, I have a question concerning the completion of the form IMM0008 ,family members. My family have been accepted for selection for immigration to quebec via the skilled worker process (my wife being the main applicant)and now we have to complete the forms like everybody else for permanent residence in canada.
I have a son whom I have not seen or had any relationship with since he was 18 months old, he is now 17 years old and I have no idea where he or his mother live and have no means of contacting them.This person obviously is not considered as a family member to us and will not be immigrating to canada with us.
I have been in contact with immigration canada,via email, twice concerning this family member,explaining that it is impossible for me to provide all the information that is required on the form IMM0008 generic. The only replies I have received,tell me that I am obligated to include this person on the IMM008 and provide all of the required information and documents concerning him.The only information I am able to provide is his full name, date of birth ,place of birth, a copy of his birth certificate and last known address(at which I know he no longer resides neither his mother).
I now feel as if I am up against a brick wall,as I am obliged to provide this infomation and I obviously cannot. Does this mean that I can no longer continue with my application for permanent residence in Canada?
I am very confused and concerned as the replies from immigration canada do not help me at all, does anybody have any idea how I can proceed from here ?
Anybodies help or advice will be greatly appreciated!!!!!
Many thanks for reading this post.
Snukiedog.