If the account is in her name it should be ok - if not think about opening a new one for her.
Sharing from experiences of dealing with debt
The greatness of a man is not in how much wealth he acquires, but in his integrity and his ability to affect those around him positively.
Bob Marley. http://kallis3.blogs.iva.co.uk
As Kallis says, if the account is in her name, even though you are the trustee, the money is hers and cannot be touched. However, if she is a millionaire, there might be questions !
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014