I called IRCC today and they said: 1. use both passport will be OK, we won't need a new TRV, or, 2. Apply a new TRV, at this time we need to submit the old passport too, they need to cancel the old one. 3. It doesn't matter if we apply a new TRV right now or later after the old TRV expired. The only difference is if we need to submit old passport (to cancel old visa) or not.
However, even IRCC doesn't need old passport, when I choose service center to deliver passport, they ask old passport if we provide any travel history which stamped on old passport. Guess IRCC still need solid evidence to verify travelling history as the last step.