Background - she's my dd1, she is 15 next week, her bio dad left when she was a baby and my dh has been her dad since she was 15mths, we are loving parents, she has a good home life, is doing well at school and has a Saturday job.
The Problem - her attitude, she's vile to us and her little sister (dd2 is 8yrs) she starts arguments at night and wakes her sister most nights. She thinks she can do what she wants when she wants. Especially in the holidays.
Recently she has tried to deceive us to gain entry to her gran's house to have a party while she was away (we caught her out and it didnt go ahead thank god) my mum has backed us up and told her its unacceptable and she needs to be better behaved. Last half term she got drunk on neat vodka, passed out and was sick alot and her brand new iphone5 was smashed. Last night was her first outing after being grounded for the planned party deception and wanted to come home at 930pm we said ok but no later as we had originally asked her to be in at 9pm, she was late and had been drinking wine (slurring, eyes dilated). We said it wasn't on and she would be grounded again (any words of advice about how long to ground her for this time? a couple of days? or longer?) she went mad saying she wasn't being grounded again, we are too strict, we can get bent, do one, that her dad isn't her dad and can't tell her what to do etc then said i'm not her mum (erm yeh ok love lol). In april she also ruined our family holiday by basically acting like we had kidnapped her even though we got her wifi so she could still contact friends, it was a 2 wk all inc hol which we have never done before so we had been really looking forward to it 
After the vodka episode I took her to the doctors to get her the morning after pill (as their were lads at the party and she had hazy memories, not full on sex but other stuff going on before she passed out!) I also spoke to the doctor about her being on the pill (she had previously been on it to calm her erratic periods but kept not taking it so didn't solve the issue) she is now taking it (i'm ensuring she is) I also spoke to them about getting her referred to Camhs (her appt is early sept) because I believe she has slight OCD (just re-decorated her bedroom and if something wasn't white enough she wouldn't have it) she is very materialistic and looks after her stuff very well (which is good) she has definate sibling rivalry issues (vile to her sister or ignores her completely, said she wishes she was never born/ was dead etc which is very upsetting for dd2 who is very sensitive) then there is the issue of dd1's bio dad who has never bothered to gain access, he is an unsavory guy, in and out of prison for violent assaults, not a good role model at all so I'm relieved he has left us alone tbh as he stalked me, abused me etc.
My question - How do I handle all of this? How do I trust her to go out? What do I do when I'm working and can't be here? How do I protect my dd2 from her sister? It's her birthday soon and we said we weren't getting her a present as such because we were doing her bedroom up instead. We have been saying for the past 6mths if she could be good for a couple of weeks we would do her room but she couldn't/ didn't manage it so as it needed doing we did it for her birthday instead of presents.
Dd1 is going to her aunts for 6 days next week so at least we can have a break but she just had a weekend at her grandparents and though she was an angel for them she has obviously come back and done this.