I have a 13 yr old stepson who is very problematic. He's currently on med. for ADHD. I need advice: ?

Aside from behavioral issues ociated w/ ADHD (focus, academics, impulsiveness) we also deal w/chronic lying (rather stay away from clinical terms as "compulsive"). My husband has had him since he was 3 yrs old. & bio. mom was rarely in his life until recently (4mths ago). His bio mom has 2 more kids w/2 diff. fathers basically my husband dedicated life for kid. Since he's always in trouble in school often is on punishment (short periods of time) other times we do not punish even though behavior is negative b/c we don't want to constantly punish him. This weekend he went to visit bio mom which she has recently been in his life & takes him for weekend 1x a month. He took something out of house that he is not allowed when Dad said why would you take this w/out permission he replied "because it's mine" (in very sy & defiant manner) Dad replied everything that is here is bought for you but does not belong to you basically right after child replied that is why I want to move w/mom. My husband was infuriated. Bio mom said she doesn't want him over there b/c even when he visits he is very problematic & disrespectful. My question is should we send him over there as a lesson so he can appreciate all the commodities he has w/us (skateboards, scooter, own room, computer, psp, games, sneakers, nice clothes, videos, tv in room, dvd player...) which he won't hav eat bio. mom's home or what should we do? One more thing child is very manipulative. Could this be a manner of manipulation?