Yes, my situation is same as yours. Myself and my wife is a PR but my son born In India. Now my wife is in India with my son.I didn't add her as a co-signer . Also Included the notarized imm5604 form along with an explanation letter.
As per the CIC, in order to Sponsor anyone from overseas, the Sponsor and co-signer, should live in Canada. These conditions don't apply oly if the Sponsor is a Canadian citizen.