Hi Asharu,
Firstly, congratulations for your baby.
Secondly, did you get a letter from you Visa Office or its just RBVO in the e-case ?
Regarding the application update, yes you will need a copy of the baby's passport (just a photocopy, notarization is commonly done for experience and other official documents). So I advise you to start obtaining the passpost as fast as you can
In the meantime, you need to send an explanatory letter to your Visa office (by case specific or email or DHL, mentioning your file number) informing them about the change in your family composition, ask them to provide you with instructions how to add your baby to your application for permenant residance.
After that, they will send you a list of required docuemnts, you will perpare the complete file and send them altogather by post or DHL.
Good Luck!
Magdy