How and when do you add a stopover to a one-way Krisflyer redemption?

Hi all, just got online and booked my first ever redemption. I’ve booked suites class from JFK to Sydney via Frankfurt and Singapore for my husband and myself departing 20th March next year. My question is…can I now ring Singapore Airlines and request to buy a stopover in Frankfurt for 18 days…or should I have rang them in the first place and done the booking through them? It doesn’t really matter either way, it just means we’ll spend longer in Canada and the US before coming home. Just thought it might be good to break up such a long trip. Any help would be appreciated.

If you have checked and found availability on FRA-SIN flight on the date you wish to fly, by all means give them a call. Ideally, you should have made the booking over the phone in the 1st place. Also, there will be a US $100 stopover charge if you booked the saver fare. On Advantage fare, its gratis.

Thanks for your help. I thought I should have but being my first redemption I just wanted to be able to do it easily online without having to ring an agent.