All these people enjoy the parade by participating in it.
People are playing instruments in a parade.
just because the people are participating in the parade does not mean they are playing instruments in it.
exists x2 x3.(n_thing(x2) & n_parade(x3) & n_people(x2) & all x1.((x1 = x2) -> exists e2 e1.(by(e1,e2) & in(e2,x2) & Actor(e2,x1) & v_participate(e2) & Theme(e1,x3) & Actor(e1,x1) & v_enjoy(e1))))
exists e1 x1 x2 x3.(in(e1,x3) & n_parade(x3) & Theme(e1,x2) & Actor(e1,x1) & v_play(e1) & n_instrument(x2) & n_people(x1))