Originally Posted by
IluvSQ
If the infant has his/her own seat, then full points required.
If the infant is a lap child, then no points required.
If the infant is a lap child then you will need to buy a ticket for him/her. Typically this is 10% (but some airlines charge more, perhaps to discourage it) of the adult fare
for the cabin you are seated in., i.e. Business Class, not economy. I suggest using something like matrix.itasoftware.com and selecting flight for exactly the same [round-trip] itinerary as you are flying specifying one adult and one infant-in-lap so you can see exactly what the infant should cost you (you can't search for just an infant, as there needs to be an accompanying adult).
Warning... expect an unpleasant surprise. It will likely be more expensive than you are expecting.
Once you know what to expect you will need to call the airline directly to book as they will have to cross-reference to your PNR.
DAK