A group of four people wearing navy blue staff shirts are standing outside while three of them are having a drink.
Four brothers stand and have a drink
The first sentence does not say what the relationship is between the four people, so we can't argue they are brothers.
exists e2 e1 p1 s1 s2 x1 x2 x3 x4 x5 x6.(exists e3 x7 x8.(Theme(e3,x8) & Actor(e3,x7) & v_have(e3) & n_drink(x8) & of(x7,x1) & n_thing(x7) & card_eq_3(x7)) & n_thing(x1) & while(e2,p1) & a_outside(s2) & Manner(e2,s2) & Actor(e2,x1) & v_stand(e2) & of(x1,x2) & Theme(e1,x4) & Actor(e1,x3) & v_wear(e1) & n_shirt(x4) & of(x4,x6) & n_staff(x6) & a_blue(s1) & Theme(s1,x4) & of(x4,x5) & n_navy(x5) & (x2 = x3) & n_people(x2) & card_eq_4(x2) & n_group(x1))
exists e2 e1 x1 x2 x3.(Theme(e2,x3) & Actor(e2,x2) & v_have(e2) & n_drink(x3) & n_brother(x2) & card_eq_4(x2) & Actor(e1,x1) & v_stand(e1) & n_brother(x1) & card_eq_4(x1))