Same question, what is your status in Canada?
This section "
Permanent Residency Obligations" is for PR of Canada to discuss about their Obligations (mostly on the physical days spent inside Canada as PR).
If you are not yet a PR, you are posting in the wrong section.
If you are an internation student, then you could apply for TRV/SOWP/study permit for your immediate family BUT the approval is never guaranteed.
If you are the mother of your child, it should show in the child's birth certificate. I don't understand what is the "custody documents" you needed since the father already passed away.
For your spouse, you need marriage certificate.