You would have to inform your IVA of this income but it is down to the company as to how they use this information.
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
Yes, it will be classed as income. I assume you get allowances in your general expenditure for the children, so check you are claiming everything --- age dependent of course: school lunches, school clubs and trips etc.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014
Creditors normally request that maintenance is sought if not already received. You are then expected to increase your payments by a percentage of this and this may actually be listed in your Chairman's Report. Check the terms of your IVA.