It sounds like you and your wife have visas now, but haven't landed? And your baby is already born?
If so, there is one thing and only one thing you can do: contact your visa office, inform them about your newborn baby, and they will re-open your case and you will have to add your baby to the visa application.
Your COPR stated that you are required to inform the VO about any changes in family composition, including the birth of a child. Do not disobey their instructions or try to mislead them.
If you attempt to land and you have members of your family you have not declared, you may be refused entry or deported after entry, losing PR status, and you could be prevented from EVER sponsoring your baby. Don't try it!
Good luck.