About 6 months ago I booked an Airbnb for myself, DH and two kids (in august). The house sleeps 6. Now my brother and his wife are going to join us for 4 of the 7 nights. Do i need to tell the owner/amend the booking? I'm not sure if the price was based on the number of guests or if it would have been the same whether there were 2 people or 6. Any one have any idea?