Have you ever fed him a scrap from your plate? One of the big no-nos here is to feed Melody anything from our plates whether we're sitting at the table or not. She never mooches from me but she does sometimes with the kids.
She never used to mooch but my sister looked after our kids for a couple of nights and gave Melody every last scrap from everyones plates and since then she (Melly) started hassling us at the table
Also if there are leftovers for her I put them into a separate container and they go into her bowl when she's not looking, hopefully that helps her dissassociate our plates with her getting something