AFAIK, SQ website only shows the booking made directly on-line, regardless the class of service.
Almost all my bookings done by SQ office. Those never showed on-line. But I can do on-line check-in. I get the confirmation by e-mail or printed at SQ office. I know I called the 800 number of SQ reservation in the US for flight changes, and the agent offered me to e-mail or fax my new itinerary.