My 7 yr old has taken to total defiance. Any tips on how to tackle?

[thatisthequestion]

no we are not a perfect family, we have fought and shouted at each other, at kids, but nothing drastic as threats of separation or leaving house or physical abuse. We have a beautiful house, totally privileged, have every gadget, kids have beautiful bedrooms, eat out, travel around the world etc. I am stay at home mom, take them out, give them individual time, spoil them, discipline them.
Now the middle DD out of 3 dds has always been a free spirit, at the age of 4,5 it was fun and independent, at the age of 6 I tried dealing with her by ignoring her mistakes and then giving her more love, showing care, but now she is 7 and worse than ever.

It's as simple as NO to everything I say. Let's go swimming, NO. Eat , NO. Let's read a book NO.
Love, harshness hasn't worked.
The only thing is they are gifted and talented but I still don't see their high IQ should be a reason for them to be rude.
I showed her consequences by not taking her to a friends party on Sunday but she cried it out and is over it, didn't change her behaviour pattern though.
Beautiful behaviour at school, is kind at heart but wont listen to me or daddy :(

Any similar cases?

There's no reason to be rude just because you're intelligent, no. :) It's a form of attention-seeking unfortunately. Middle children (sweeping generalisation alert) often seem to struggle with not having the authority of the eldest or being cossetted like the youngest and strike out for individuality in the form of bolshiness.

I think you have to go with a twin-pronged approach. Don't let on that the 'no' rubbish is impacting on you at all, but make it clear that treats like reading books and swimming are being missed out on because she's being a pain. "This is hurting you more than it is hurting me" etc. And on the other side, if she shows so much as a glimmer of cooperation be very positive. Also, take it in turns with DH to spend time with her one on one doing things she enjoys - even if that's playing a computer game btw - and talk to her one on one, without her siblings (that also goes for the other two). Everyone needs to feel that they have their parents' full attention from time to tiem, especially in larger families.

Thanks a lot cogito, she does not want to be separated from her elder sister so doesn't come with us alone even when offered, occasionally I do lie in bed with her as that's what she loves. Doesn't understand the reward system that if you are nice I will lie in bed with u at bed time, despite me explaining she keeps on not listening.
Tell her not to play with something , she would still carry on, so sometimes I physically stop her but it can b like battlefield in the house and not pretty for the younger one to look at with her crying so I keep calm and keep away :(.

Will try and show it doesn't bother me, may be clean the table even if she hasn't eaten as she was busy messing about while the rest f us ate? But the fear is that she may go without eating as she won't care anyways ........
Any input is appreciated !!!!

Perhaps you could try being more definite in your speech? You've prob already tried it though. Instead of saying 'Let's go swimming' try 'we are going swimming now' or 'get in the car, it's time for swimming'.