PURPORT

Wife of Dronacharya Kripi is the sister of Kripacharya. A devoted wife who is according to revealed scripture, the better half of her husband, is justified to embrace voluntary death along with her husband if she is without any issue; but in the case of the wife of Dronachrya she did not undergo such trial because she had her son as the representative of her husband. A widow is so-called if there is a son representative of her husband existing. So in either case Aswatthama is the representative of Dronacharya and therefore, killing of Aswatthama is killing of Dronacharya. That was the argument of Droupadi against the killing of Aswatthama.