I'm not sure what you're asking.
From what I understand, you're sponsoring your wife, son and daughter - born when you were not Canadian, is that correct? if your VO has asked for a second medicals it means that they are most likely looking at your file now.
In the meantime, did you have another baby? if you became Canadian before the birth of your baby, then your baby is Canadian. You need to ask for his/her certificate of Citizenship, in the application, add proofs that you are in the process of sponsoring the rest of your family. Hopefully it will speed up the process. Once you have the certificate, apply for a temporary passport for your child, and he/she can go to Canada together with the rest of the family once they have their PR.
If your baby was born before you became Canadian, then you need to ask her/him to your current application. FIll out the form for main applicant and add another dependent with all required papers.
Good luck,
Sweden
