Who is who on all the Gone series books including Gone Hunger Lies and Plague covers and back covers?

Ok, on Gone it's Sam, Astridon the front and Diana and Caine on the back. On Hunger there's Diana and Caine on the front and Sam and Astrid on the back. On Lies it's Sam and Astrid on the front and on the back it's Caine and Orsay most likely. And on Plague it's Astrid and Caine on the front and on the back is Sam and not sure who the other girl is.