Ability to Edit Invoices After an Order is Placed

Can someone please help me figure out how to be able to edit invoices after an order is place? This is standard functionality in Volusion (that I'm transitioning FROM to OpenCart), but I can't figure out how to make it happen in OpenCart. I'm on version 1.5.x... I read on a forum that being able to edit invoice details is a feature that's meant to be built in, but if that's true, I can't figure it out. Thanks for your help! I need to be able to edit everything, product codes, descriptions, options, price, qty, etc. etc. Customers orders change sometimes and creating an invoice from scratch is not acceptable. As well, sometimes you are selling products with specs etc. that are not products on your site. You must be able to edit invoice details in some kind of edit mode.

Thanks,
Jason

would also like to get help with this topic. than kyou.