Originally Posted by
MSPeconomist
... LGA-YYZ operated by Westjet but sold as a DL codeshare. I assume it would leave from a different area of LGA from the terminals DL use, probably the central terminal, so that if there's an obvious delay, there would be no opportunity for the OP's two tickets to be changed to LGA-DTW-PVG, all on DL of course.
WS operates from the D gates (D6, iirc) at LGA
even though I did something similar a couple months ago (the same 0610 flight from LGA; 0945 trans-border departure on WS from YYZ; carry-on only), I still wouldn't second OP's thought where a high-cost TPAC ticket is in the balance