Debts do get sold on at various points during your IVA. Nothing to worry about as they are bound by the IVA and can do nothing.
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
'Bad' debts often get sold on as 'job lots' auction style (think of those ebay warehouse pallet returns) and the buyers pay pennies for them. It will have no impact on you regarding the IVA .... but do keep an eye on your defaults, as sometimes the new owner will register a default with the wrong date.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014 http://foggy.blogs.iva.co.uk