Children are listening to a man in a blue shirt.
The guy is the children's grandfather.
Just because they are listening to a man doesn't imply that it is their grandfather.
exists e1 s1 x1 x2 x3.(to(e1,x2) & in(x2,x3) & n_shirt(x3) & a_blue(s1) & Theme(s1,x3) & n_man(x2) & Actor(e1,x1) & v_listen(e1) & n_child(x1))
exists p1 x1 x2 x3.(n_grandfather(x3) & of(x3,x2) & n_child(x2) & n_guy(x1) & (x1 = x3))