§ 6-5.7 Posthumous children (a)  Where a future estate is limited to children, distributees, heirs  or issue, posthumous children are entitled to take in the same manner as  if living at the death of their ancestors. (b) A  future estate conditioned upon the death of a person without  children, distributees, heirs or issue is defeated by  the  birth  of  a  child conceived before but born alive after the death of such person.