passport stamp for Canadaimmig

Should the whole family go to Buffalo to have passports stamped for the purpose of Canada immigration or just the principal applicant? I just mailed out all my supplementary documents on November 1. However, my stay in US will expire on Jan 22, 2005. I hope I'll get passport request in Jan, then fly to Buffalo for visa. I worry that I won't have enough time to wait for passport request. Then, everything will be messed up if we return to China. I don't really know what to do. Worry to death! Any information is highly appreciated.