One woman sits on a outcropping of rock while one takes a picture and the third looks down.
The women are sisters
Just because the two women are interaction with each other that does not mean they are sisters.
exists e1 p1 x1 x2 x3 x6.(n_third(x6) & exists e3 e2 p2 x4 x5.(exists s1.(Theme(s1,x6) & a_down(s1)) & Topic(e3,p2) & Actor(e3,x6) & v_look(e3) & Theme(e2,x5) & Actor(e2,x4) & v_take(e2) & n_picture(x5) & n_thing(x4) & card_eq_1(x4)) & while(e1,p1) & on(e1,x2) & of(x2,x3) & n_rock(x3) & n_outcropping(x2) & Actor(e1,x1) & v_sit(e1) & n_woman(x1) & card_eq_1(x1))
exists p1 x1.(n_woman(x1) & exists x2.((x1 = x2) & n_sister(x2)))