I just discussed the same issue with my colleuge. She gave birth in HK (her 1st son) then get HK passport. At that time she and her husband are both PR. Then later, she become citizen and get the Singapore passport. And she also help her apply 1st son to get passport. Now her son has two passport. Amazing to me, I thought her son need to gave up the Singapore passport.
But for her 2nd son is born in Singaopore, so she said only can get Singapore passport. Very very difficult to get Hong Kong passport la.
I check with her because I also want to know whether my baby can get Hong Kong ID card (or passport. Seems that my baby can only get Singapore passport.
A child is eligible if he or she is:
a. born on or after 1 August 20045;
b. a Singapore Citizen or becomes a Singapore Citizen6;
c. the first to the fourth child born alive to the mother7; and
d. the mother is lawfully married to the child's father8.