Since both Airlines are Star Alliance I figured this would be easy. I have looked to add my United MileagePlus number in the Booking on Singapore Airlines but United doesn't even show up in the list. I went to the Add Partner Programmes Link on Singapore Air web site and had the same issue. I know they do code share on some routes and they are both Star Alliance members. Does anyone else have this problem and have you found a solution to it. It would be a waste to not collect the United miles for some extensive travel on Singapore Air.. Thanks.