FFS OP, With each of your replies, it's gets more depressing.
I really hope for your sake, that your children are never in this position.
You've known this since October and done fuck all about it.
You don't even need to involve SS, as a quick call to the school to explain the situation, whilst your Nephew was staying with you, would have been all that was needed.
This poor boy is crying out for help, from everyone around him, yet you're all doing fuck all for him.
What does he have to do to get you to listen?
I have a DC with additional needs, and lots of allowances have to be made. I'm also helping a family member who's going through a horrendous illness at the minute, yet I could spare 10 fucking minutes to call the school about my desperately I'll Neice/Nephew.
You think that having 4 children is an excuse to do nothing for him. You've all let him down. And when you know that someone's needs are being neglected in such a way, like this, you're just as neglectful as everybody else.
He clearly hasn't caused you any problems whilst staying there, so his Mother was right. That's clearly what you all think that a teenager needs. Well it isn't!
This thread is the most difficult one I have ever read on here. And for you to justify doing nothing, because of another thread on here, says everything about you!
I hope this poor boy is being monitored at School already and this could be taken out of all your hands soon enough.