Debts often get sold on. The new "owners" are bound by the IVA as were the original creditors. Pass the details to your IP to sort out.
You might get demands for payment, in which case tell them about the IVA ( you may need to send copies of the paperwork ). Many debt purchasers do not realise there was an IVA as they purchase the debts, for pennies, in unseen job lots (like pallet returns). Some do realise but try it on anyway !!
I am not qualified to give advice and can only state my opinions, based on my IVA experiences.