@JonSnowsWife
The OP has already said they don't know all the facts yet somehow knows the child doesn't have sens/isn't adopted but does know that the person committed fraud even though they don't even talk to the mum well enough to know any of this.
Even if the OP doesn't know if the child has sens etc, she is still within her rights to report this family. As has been said (many times on this thread,) if that's the case, then all will be fine, will it not? Or would you rather children who live 2 minutes walk from the school should have to travel 5-10 miles to school, because someone is a massive liar.
@CoffeeBreakIn5
The whole school admissions crap is a horrible experience made worse by people who lie and cheat. If a parent decides to lie and cheat then they are the ones who are putting the child's school place at risk once they have started, not the people who end up reporting.
Exactly! It's like if someone is cheating benefits, or stealing from their employer etc, and someone reports them, and the person committing the crime gets fired or taken to court etc, it's not the fault of the person reporting it; it's the fault of the numpty who committed the 'wrongful' act in the first place!!!
Reminds me of a time when a friend of mine told her friend that her husband was seeing another woman. She spied on him and caught him out, and she left him, took the kids, and started divorce proceedings. He lost everything. Even his own 2 kids (10 and 13 then,) wouldn't talk to him. Still won't, 3 years later.
Guess who said husband blamed? You guessed it; the friend - for telling his wife about his affair. None of his downfall was his fault, or the other woman's. It was ALL the fault of the friend! 
This is a similar case. Some people on here are aiming bile at the OP for wanting to cause trouble, and ruin this child's education etc, but if the child's life IS upheaved, the only ones to blame will be the parents for lying, and cheating the system.
Upshot is OP, DO report this. If the family are doing no wrong, then nothing will happen, will it?
And ignore the people saying 'mind your own business;' it IS your business AND everyone else's! And the 'you have too much time on your hands' chestnut is getting boring now; it's like there's a fucking echo in here! 