I have a 8 years old kid with ADHD
… ADHD kids lie much more than average .. The reason behind that is that they make a lot of mistakes due to lack of self control .. so .. they believe that they are bad .. and wish to be good.. They lie to beautify their picture in front of others.. Remember that they get criticized so much every day.. this maximizes their tenancy to lie .. Try to ignore small mistake as much as possible.. Be proactive not reactive ; ensure you are feeding him always with the code for conduct and good manners not only when he make mistakes .. but always.. and keep reminding him -be patient- .. Be a good example ! Make sure you don’t lie before you ask him not to 🙂
Regarding Defiance, your kid is under pressure .. maybe he gets orders more than he can cope with .. maybe his ability to get things done the right way is limited. .. he might be in need of coaching how to get things done right.. Remember that ADHD is self centred.. They do not tend to help others .. this needs coaching and patience .. also they do not tend to learn anything serious other than having fun..
Maybe your kid is suffering of rejection by school teachers and students .. maybe neighbours also .. Help him build good relationships and love himself .. Expose him to activities that unleash his power and talent .. Help him explore himself .. this well raise his self confidence which is the till gate for acceptance… Help him by teaching him good communication skills .. it takes time but it works.. Listen to him .. Try to understand what he feels and think about himself and others..
Also be thoughtful that ADHD people get bored quickly .. not easy to complete any job .. Give him breaks .. Agree with him on the breaks .. ADHD people are sensual.. They need love and touch.. get close to him .. show love .. hug him a lot .. tell him that you love him repeatedly .. let him open up and have his say ..