These three boys are trying to carry some wood.
They are carrying wood for their grandfather.
The first sentence doesn't imply who or what the wood is for, it says nothing of a grandfather.
exists e1 p1 x1.(n_boy(x1) & card_eq_3(x1) & Topic(e1,p1) & Actor(e1,x1) & v_try(e1) & exists e2 x2.(Theme(e2,x2) & Actor(e2,x1) & v_carry(e2) & n_wood(x2)))
exists e1 x1 x2 x3.(n_grandfather(x3) & of(x3,x1) & n_thing(x1) & n_thing(x1) & Theme(e1,x2) & Actor(e1,x1) & v_carry(e1) & for(x2,x3) & n_wood(x2))