Hi Georgy,
In general as far as savings are concerned the DWP differentiate between legal and beneficial ownership.
The £10,000, as it is in an ISA is owned legally and beneficially by the child. The remaining £5000 is in the child's name so the DWP would have to prove it was not actually the child's. So I don't think the DWP can say that the capital is yours.
But one thing you cannot do is transfer lump sums of your own money into a child's account with the express intent of reducing your savings. This is termed deprivation of capital.
David
David
Nothing on this board constitutes legal advice - always consult a professional about specific problems 
