The point of these procedures is that basically under common law (and civil law of many, many countries), for some types of things you are expected to provide legal notice, and legal notice usually means sending a registered letter (a letter which gets a receipt that it has been delivered) and in some cases (eg whereabouts unknown) to place a notice in newspapers or public register/gazette.I did not send letter or mail to the registered address however, I called her on more than a dozen occasions, sent emails to her and her sisters, sent text messages and whatsapp calls but no letter to mailing address. ...
I am not sure if these documents would work or the IRCC is going to act strictly and refuse my application?
You should speak to your lawyer in Pakistan about - ideally - providing some type of notification to the mother acc to local legal procedures, eg pls, hereby request to allow the child to be examined, this would allow the child to potentially immigrate to Canada in future, pls respond.
[At least I assume this was the point]