A group of children in the ocean.
The children are brothers and sisters.
You can not infer they are brothers and sisters.
exists x1 x2 x3.(n_ocean(x3) & a_topic(x1) & in(x1,x3) & of(x1,x2) & n_child(x2) & n_group(x1))
exists p1 x1.(n_child(x1) & exists x2 x3 x4.((x1 = x2) & subset_of(x4,x2) & n_sister(x4) & subset_of(x3,x2) & n_brother(x3)))