@Sharktale2020 It's really rubbish of her, especially as she appears to have adult children (four drivers living in the house?). However, you can't control what other people do, so try and channel that anger into something positive for your niece.
Make it clear to her that she has a place with you if and when she needs it - even if she initially chooses to go into care, keep the offer open. Poor kid sounds like she needs someone she can rely on!
And do speak to children's services about support to make the adjustments to the house - believe me, they would very much rather pay to help you put a partition wall up than have to find a placement for a 14 year old. It may take a while to get through the red tape, but they will support that eventually!
The posters who have been saying that anyone who could but wouldn't take a niece in to prevent them going into care are selfish are correct - I am amazed at the number of posters who think it is OK for the sister to do this to protect her peace or some shite.
To agree with the sister or even worse say they wouldn't take a niece in either in case it caused detriment to their own children and their current nice life shows a serious lack of empathy and I have to wonder whether they care whether their own children would end up in local authority care should something happen to them and their other parent.
They may think they've made arrangements, but what happens if they people they have made arrangements with decide its too difficult, or it is disrupting their lives too much....it astounds me that people who have their own children can have that attitude towards another child who is a very close relative - particularly when they have already been living with them for a while.
I can sort of understand where someone who is childless is coming from with a decision like that, but not someone who has children of their own.
I would take my nieces and nephews in an heartbeat if it mean they didn't have to go into care!
And before the 'when are you doing your bit' crowd come after me - we are the named guardians for my nieces and nephew should anything happen to their parents, I work in children's services and chair a children's charity board so do my bit on a day to day basis.
When we semi-retire and I have more time, I fully intend to emergency foster, because I have seen first hand through my work what happens to these children, so if I can make even a small difference to children who need it then I will!