Ok so this holiday is going to be intense
Nice is hot, hot to walk in all day, oh and of course the walking! Finding restaurants with kids in tow, the pack up will need to be mighty for the tudor feast those kids have for lunch/snacks.
Trains/travel/buses or tubes again such a delight with hot tired kids!
Her only saving grace will be the air bnb if they've booked a decent one, I 100% prefer them over a hotel with kids in a city, plus there is a washer/dryer small things like that so you don't need to pack loads. You can do take out and eat it in your pants ( if you're Feebs)
However happy kids=happy holidays! She needs to do her time and sit through chocolatte like the rest of us did, that's what parents do!