Lots of different comments but Alarm Bells when l read ‘have to sell the house pay off the mortgage and buy an apartment’ WHY??  Having owned both the apartment overall was more costly. Not only rates to pay but Body Corporate Fees etc. yes no garden but l only pay $60 a month for a gardener. An apartment building may offer a gym a pool etc but you are paying for something you may rarely use. 18 year old needs a part time job and start contributing to the household. Time to have a taste of pending responsibilities