Reply To: Companion Voucher with multi city

[JDB]

As above, you can’t book Avios open jaw itineraries online with BA, although you can for cash tickets. The fundamental IATA fare construction rule for open jaws is that the distance of the ‘surface’ sector cannot exceed that of either flight. In this case, the distance between Venice and Istanbul exceeds the distance London to Venice so that itinerary is not allowed as an open jaw; it is two singles.