I am a little confused. Are you keeping the weekend reservation and having the long term guest book around the 2 days? Have you spoken with the weekend guest and given them some incentive to cancel such as paying all unrefundable fees? Your long term rate will not be applied by the system for a booking less than 29 days. Air BNB fees and any taxes are based on the rate charged, so if you want to accommodate the long term guest, just send a special offer and the fees will be adjusted accordingly. Make sense?