My sister is 12yrs old and currently living with my step-dad and her nan (step dads mother) this is due to losing our mother she passed away Dec 09, my mum had a serious horse riding accident Aug 08 prior to her accident she had split with my step-dad as he was a very nasty controlling man, example from mine and my eldest sisters view he would make us clean cook work and take our wages off us, he was nasty to our mother following her around shouting abuse calling her names and checking all our mobile phones he conviscated my phone from me when I was 18 and also my mums mobile and she was 46 at the time! Now my little sister is living with him he makes her clean, cook etc she does not even have her own bedroom as where they live is only a 2 bed (its the nans place). My sister is so unhappy she has told me she wants to be with me and my family. I am almost 25 and have 4 children of my own (all very well looked after and happy). Also my step father lets her stay up till gone 2am even on school days, I am so worried about her and her wellbeing. I really need some advice on how to go about getting some kind of contact with my sister if not full custody.. My step father refuses me access (he has never really like me as I speak my mind and tell things how they are) My mum would be so mortified by all this. This man ruined my mum's, mine my eldest sister and now my little sisters life.. Please if anyone can give me some advice id be so grateful.
Many Thanks

Where are you from? How was custody granted to your ex-step-father?

Where is the natural father? Unless the step father adopted the step children he has no rights to them.

I would consult a Family Law attorney to see what the best way to proceed is. But I certainly think there is a good possibility for you to get custody. One possible scenario is to get an order granting you temp guardianship, then go to the child's school and pick her and take her home. But you NEED to make sure you have the law on your side before you take any action.