How to choose award seats on various Star Alliance carrier flights when redeeming through Krisflyer?

I have just booked a RTW award flight through Krisflyer. All but one of the flights is through another Star Alliance carrier partner - just one is through Singapore Airlines.
I can choose my seat on the Singapore Airlines flight but cannot choose seats for the other carriers via the Krisflyer website.
Is there a way I can select my seat on the other flights?

Hi,

I would probably try to get the reference/confirmation/e-ticket number for the different legs. e.g. if you are flying Thai Airways, ask for the Thai Airways number from Krisflyer and then use that number on Thai Airways website or ring them up to select the seats.