Under previous legislation it was ruled that a trust is created by the IVA, which survives after completion. It is this trust which empowers an Insolvency Practitioner to deal with the business of the IVA after it has been formally completed and the IP has, for all intents and purposes, relinquished his role as Supervisor.
More recent cases have ruled that refunds like PPI are still due to the IVA, via the trust, after completion, on the grounds that they existed during the IVA, albeit not known about at the time. The same argument would apply if you discovered, well after completion, that a rich relative had died prior to or during the IVA, leaving you a bequest. This bequest would also be due to the IVA trust. In theory, this lasts in perpetuity, in practice IPs are only required to keep records for 6 years after completion and, so, would be unable to distribute anything after the records had been destroyed.
My opinions are merely that .. opinions based on experience. Always seek professional advice.
IVA Completed 23rd July 2013 .... C.C. 10th January 2014