How long is the flight?
I regularity flew with my three alone between Europe and California plus a connection. They're close in age.
The secret to flying with toddlers is to keep them rested, fed and watered (not thirsty, in other words). No messing with their schedules or any nonsense before leaving.
Good quality baby carrier is a must. A "crotch dangler" like a Bjorn is not useful. Get something more practical and comfortable.
I found ditching the stroller and using a luggage cart MORE useful than dealing with that extra gizmo.
Mentioning this, is there any way to get a car seat at your destination? I used to keep one at my parents when mine were little. I traveled with just one.