Note that it's basically impossible for DL to have direct flights to PTP currently with AF flying MIA-PTP route. DL metal flight numbers come from different ranges than codeshare flight numbers on partner metal. DL codeshare numbers on MIA-PTP/PTP-MIA flights are DL8624 and DL8532. As noted above, just because there are no direct flight numbers doesn't mean you can't book connecting itins on a single fare component. The AF A320s that do MIA-PTP also bounce between PTP-FDF, FDF-CAY, and CAY-BEL.