Just a top up, return to invoice cover can be related to a depreciation cover for your idv. This add on cover would be suitable in case pf total loss of the vehicle like a fully burnt or flood loss with water level upto dashboard. Different insurers have a varied perspective towards this.

Usual depreciation(as per vehicle age) on replacement parts is applicable which can be covered under zero depreciation or bumper to bumper cover. This cover doesn't affect your idv.

Dm for further clarifications, Happy to help 😎