I have seen but not photographed Franklin’s Gull.
I have seen Common Black-headed Gull outside of Southern Africa
Gulls still to be seen in Southern Africa: Heuglin’s Gull, Slender-billed Gull, Black-legged Kittiwake, Sabine’s Gull
I have seen Gull-billed Tern in India.
Terns I have seen but not photographed are: Roseate Tern, Black-naped Tern, Damara Tern.
Terns to be seen in Southern Africa are Royal Tern, Lesser Crested Tern, Arctic Tern, White-cheeked Tern, Bridled Tern, Black Tern.
Other birds in this group still to be seen are: Brown Noddy, Lesser Noddy, Subantarctic Skua, South Polar Skua, Pomarine Skua, Parasitic Jaeger, Long-tailed Jaeger.