A boy wearing a red cloth as a headband is having another person write on his cheeks with red magic marker.
The sister pretends to put makeup on her brother.
Just because another person was writing, it does not imply that the boy's sister was writing, or that he even has a sister.  Writing on a boy's cheek does not imply that one pretends to do anything.  A magic marker is not necessarily a form of makeup.  Stating that a person wrote on her brother implies the person's gender, but simply referring to someone as a person does not imply any specific gender.  Just because the boy is male, it does not imply that he is another person's brother.
exists e2 e1 p1 s1 s2 s3 x1 x2 x3 x4 x5 x7.(n_person(x7) & with(e2,x5) & n_marker(x5) & a_magic(s3) & Theme(s3,x5) & a_red(s2) & Theme(s2,x5) & on(e2,x4) & n_cheek(x4) & of(x4,x1) & n_male(x1) & Actor(e2,x1) & v_write(e2) & exists e3 x6 x8.(Theme(e3,x8) & Actor(e3,x6) & v_have(e3) & n_person(x8) & -(x8 = x7) & n_headband(x6)) & as(e1,p1) & Theme(e1,x3) & Actor(e1,x2) & v_wear(e1) & n_cloth(x3) & a_red(s1) & Theme(s1,x3) & (x1 = x2) & n_boy(x1))
exists e1 p1 x1 x3.(n_brother(x3) & of(x3,x1) & n_female(x1) & n_sister(x1) & Topic(e1,p1) & Actor(e1,x1) & v_pretend(e1) & exists e2 x2.(on(e2,x3) & Theme(e2,x2) & Actor(e2,x1) & v_put(e2) & n_makeup(x2)))