Unique receiving process for Drop Ships (or even normal POs)

Folks ..... Need help. Client has a unique scenario. For a drop ship scenario (or even a normal PO scenario), the supplier is being told to deliver goods at interim location of a service engineer who will then take it to customer site. it is deemed received only when at customer site.

How can this be achieved w/o customization ? We do not want to add engineer location into as a site under customer nor add locations and not have to use also the 2 step standard receipt routing where 1st step is by engineer and 2nd step once he reached customer site.