Just list the amount you are offering and from where the funds are being obtained. You may need to provide an up to date valuation and mortgage statement and if there are any reasons for the offer such as reduction in earnings, provide some back up to the IP.
Make it clear that the third party funds are for the purposes of a full and final only. In the event that the offer is rejected the third party will retain the funds and they will not be available for the IVA.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014