Would be the best idea especially given your other post and concern about impact of reduced payments.
IVA started March 2011, Completed March 2016 and certificate issued 11 days after final payment. It was not always easy but then some of the best decisions aren't.
Is there any equity clause to fulfill? If not then I would do as others suggest if son wants to pay the final payments go with it and it'll soon be over. Good luck for a smooth conclusion to your IVA
IVA final payment left the bank on the 26th January 2013...looking forward to a debt free future.