It is possible that your IP can negotiate an extension of 12 months instead of a restriction on the property, but he could also fail the IVA. This aspect should have been dealt with right at the start of your IVA, so there is some fault on their side too !
If they insist on the RX1 mention to the wife that, if the IVA fails and your creditors make you bankrupt, the house is at risk of being sold out from under you.
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