My SS9 driving us crazy trying to get whatever he wants by lying and manipulating adults. 
He has developed two faces, can say that he spent a wonderful weekend with us and the minute he goes home tell his mother he did absolutely nothing but staying in his rooms. 
In april, he sent "SOS danger" to evil ILs just because his father asked him to better wash his teeth. Adults that surrounded him (ILs, maternal grand parents etc..) take his words for truth and he starts to enjoy create drama. 

Next time he comes home, i just dream of telling him : 

" SS, welcome home, 
The last time you went here, father and I planned a special week-end and actitivies for you. However, when you got back to BM, you told her your father didn't anything with you and you were bored all the week-end. 
We can't tolerate these lies anymore. Enough is enough. Ok, life doesn't go as you want, ok it's hard, ok you have hard time accepting your father had another child. But that doesn't excuse your untolerable behaviour. You have NO excuse, and you won't be forgiven for that. 
Aren't you ashamed of badmouth your father anytime you have the occasion ? Aren't you ashamed of sending "SOS DANGER" to MIL when your father just asks you to brush your teeth. 
Listen carefully, you won't be forgiven for any lies. Your father is tired trying to male whatever he can to make you feel enternained. He is even more tired of hearing that whatever he does, the only thing you will to is to deny all his efforts with you. 
You said you was bored last time. We have decided that this time, you will discover what to "be bored" means. 
All your activities will stop a 6 pm, at the end of activities center. No more extra, no more ice cream outside, no more gift, no more shopping, no more playing. 
Your father is TIRED, and I'm TIRED TOO.

Parent's job isn't to please and untertain their child. Parent's jos is to EDUCATE, show the right way, and teach VALUES. 
 

Obviously, you need some extra work on that. Obviously you need to realise that the only one to get in trouble with lies will be yourself. 

For your 10th birthday, we planned to give you a motor quad. That gift is cancelled too. You will have a birthday gift of course, but not so expensive than a quad. 
Your father and I are not stupid idiot working all day long to reward a manipulative JUDAS that doesn't care if he badmouth his OWN father. 
With the money we were supposed to buy your cancelled quad, we have decided to go on HOLIDAYS just the two of us. Just for rewarding us of all efforts we are doing for our family. We decided to gifted ourself. 
 

Now, your "i'm sorry, forgive me" doesn't work. We won't forgive you, we won't forget at all ! Every word that comes out of your mouth will be checked before, because we can't trust you. 
 

And just one thing. You can tell and ask whatever you wants to MIL and SIL. We don't CARE. Our home, our money, our RULES. We don't care about what they think, we don't care if they belive you. That won't change anything here, except for you getting in more trouble with us. 

You'd better to change your behaviour boy, because trust me, we are not idiot victims. " 

Waou, even virtually, that's sooooo good !