IRCC know about the address as the letter has Canadian address for all, even though when i updated the dependents address to mentioned they only dependent are in CanadaThen he has to land first.
Did you update the addresses of dependents?
I believe that he will send passport for stamp/COPR and once he landed in Canada, dependents will get PPR/virtual landing instruction in Canada.
But others who has went through this process can confirm. Make sure that IRCC knows that dependents are in Canada and need to land after PA landed.