I'm not recommending both ways. You didn't read my post correctly or can't understand.

Try to not mess with their schedule as much as possible. If they sleep before the flight somehow, in car on the way to the airport, in the boarding area in the car seat or stroller, all the better. Don't keep them awake in the misguided effort to get them to sleep on the plane. This often backfires, even without a delay.

It's not fun when your flight schedule clashes with your children's sleeping and eating schedules but the trick is to survive anyway you can.

Please don't sleep train in transit. Wait for that once you're on the ground. I'm sure other passengers would not appreciate letting them "cry it out"!

Remember that if they're both lap babies, you probably can't sit in the same row so arrange your seating accordingly ahead of time. If they have car seats, make sure they're not about to outgrow them just before, or during your trip. 14 months is the age many outgrow infant bucket-style seats. They also might be more comfortable in convertibles on the plane (and in the car at your destination).