We live in a terraced house and our next door neighbours recently asked if we could have a tree in our garden pruned, as it was casting shade on their garden. We were happy to do this and declined their offer to pay costs. They have now said that another tree, a rowan, creates an unbearable smell when in flower and could we have that removed too. It's not something I've noticed, but I do have a poor sense of smell. I know they are being sincere when they say they find the smell offensive. They have offered to pay for its removal, but would it be reasonable to ask they pay for its replacement too? They are nice neighbours and I don't want to create ill feeling. But it would cost us several hundred pounds to replace and I rather like it.