One child holds another child's hand as the second child slides down a blue side face forward.
Two children hold hands while one slides.
A person usually holds something in a hand.  So when a child holds another child's hand, two children hold hands.  The second child is one of the two children.
exists e1 p1 s1 x1 x2 x3.(exists e2 s2 s3 s4 x4 x5.(a_forward(s4) & Manner(e2,s4) & a_down(s3) & Manner(e2,s3) & Theme(e2,x4) & Actor(e2,x1) & v_slide(e2) & n_face(x4) & of(x4,x5) & n_side(x5) & a_blue(s2) & Theme(s2,x4)) & n_child(x1) & n_child(x1) & n_child(x1) & a_second(s1) & Theme(s1,x1) & as(e1,p1) & Theme(e1,x3) & Actor(e1,x1) & v_hold(e1) & n_hand(x3) & of(x3,x2) & n_child(x2) & -(x2 = x1) & card_eq_1(x1))
exists e1 p1 x1 x2.(exists e2 x3.(Actor(e2,x3) & v_slide(e2) & n_thing(x3) & card_eq_1(x3)) & while(e1,p1) & Theme(e1,x2) & Actor(e1,x1) & v_hold(e1) & n_hand(x2) & n_child(x1) & card_eq_2(x1))