Depending on your preferred flight carrier ......you should be fine.
As much as possible ,avoid any Arabian carriers because of your babies.
Get some form of temporary jackets for them......even though the tolerance level is low but it's good to have for their temporary use on arrival before you get suitable ones for them.
Make sure you have shoes for them that will temporarily
shield the winter at the airport for them too before you get winter shoes for them after arrival.
Medications .....medications ......have them handy even if you have to look like a chemist/pharmacist ;D.This is necessary before you get your health cards depending on which province you land.....it will be mostly needed in provinces where it takes 3 months from registration date to get your health cards.
Even if you're going to provinces where the health card will be available for you immediately (i.e Alberta ),you still need drugs for immediate attention to your babies for cold,cough and catarrh .
Just like you said,you and spouse can endure but be careful not to expose them unnecessarily because their immune system to cold,catarrh and cough may still be low.
I think you should go with handy food for your kids too especially through out the duration of the flight........prepare well for this stuffs if you're taken any Arabian carrier because of their long flight periods.
For EUROPEAN carriers ,the cumulative flight period is around 16hrs and should be fine for you guys to deal with as opposed to average of about 30 cumulative flight time for Arabian carriers ;D
Cheers.
Thank you for the advice. You are well appreciated sir. God bless