There is on doubt that the son of Dhritarashtra (Duryodhana ) has burnt to death the heirs of Pandu, with the full knowledge of Dhritarashtra, else he would have been prevented (by his father).
विदिते धृतराष्ट्रस्य धार्तराष्ट्रो न संशयः। दग्धवान् पाण्डुदायादान् न ह्येनं प्रतिषिद्धवान्॥