Hi Pete and welcome to the forum.
I am so sorry that your marriage is being effected by an IVA which should have been adapted to take into account the loss of benefit income from day 1 - when it was apparent that your children would be leaving school at some stage during the five years.
I honestly do not understand what Blair Endersby are saying in suggesting that your wife takes on all of the debt. Your wife can only be deemed responsible for the debts which she is liable for (including joint debts).
Assuming that your IVA's allow for variations within the first two years (and some do not as a result of creditor modifications), you must instruct Blair Endersby to put forward a variation to the original terms if this will still return a viable dividend to the creditors.
Can I ask what monthly payment you agreed to pay and what you feel you can pay now, and also the level of your creditors?
Regards, Melanie Giles, Insolvency Practitioner for over 20 years.
For further details contact me at
http://www.melaniegiles.com and view my IVA blog at:
http://melaniegiles.blogs.iva.co.uk