Hello everyone

Looking for a help with booking extra seat with SQ using miles which involves SQ/TK Star Alliance award.I want to do this for luggage allowance because 2 Y tickets get more luggage than one business and it is lower number of miles.

You obviously can't do it online, but I want to know what exactly should be told to the agent over the phone AND make sure that you not only get the extra seat, but extra seat AND additional 30kg of luggage allowance.

If you have such experience, please share.

Thanks