I suppose if the kids, took out the student loan, as they can apply for it, then they would be paying mum and dad rent,food, contribute to wifi, electricity,gas, cell phone, etc etc. Since the kids have taken out the loan, its NOT YOUR LOAN. if the NISA grows, you could make enough to help pay off the student loan for the kids.(if you wish) Or you just allow them to pay off the loan as per student loan.and the very ultra low rate. ( of course this is basically) just replacing, cough cough, YOUR OWN MONEY, your putting into the NISA. The interest doesnt start accruing until they graduate.
I'm not sure it fraud, if the student loan is the students, and there are two types of loans, one loan is then the students live "at home", and the other loan is the one where they live away from home.