Singapore Airlines KrisFlyer - Too late for stopovers?

Question: if someone books LHR – SIN – AKL (rtn) and later finds out that the fare allows 2 stopovers in SIN, can these be included retrospectively?

Thanks everyone.

If you have a flexible ticket, no problem. If not, you will have to pay the change fee.

assuming of course there is still availability in the required booking class

assuming of course there is still availability in the required booking class
Yeah, if not, fare diff would be required.