I can say right now if there is no wind and I burn in my fire pit the whole upstairs will smell like smoke for 2 days because the smoke goes right up to my eves and into the attic. If they added onto the house and its higher then your chimney then they will have the same issue when the wind is right.
I don't know how much more height you would need to add to get it above there house but if it isnt too much you could offer to try that if they want to pay for it.
I don't know how much more height you would need to add to get it above there house but if it isnt too much you could offer to try that if they want to pay for it.