To be fair the description does say it was supplied in the USA and was bought out of a collection into Belgium ownership.
Ghia took cars from the Fiat production line and modified them. As I understand it you need to verify who bought your Fiat, or if it is part of a block purchase, to find out if it went to Ghia to become a Jolly. It is more than likely the same sort of thing happened with Morreli, though they might have intact records. I need to pursue Fiat and Ghia to try and establish the credentials of my Jolly, though it is thought it can only be part of one of two orders, being a particularly odd one. I do not know if all Jolly were ordered prior to construction but it would seem likely. This does allow the order to be followed back on rare versions if that information is available.