One verse

Srimad Bhagavatam 1.7.45

1.7.45

स एष भगवान्द्रोण: प्रजारूपेण वर्तते । तस्यात्मनोऽर्धं पत्‍न्‍यास्ते नान्वगाद्वीरसू: कृपी ॥ ४५ ॥

sa esa bhagavan dronah praja-rupena vartate tasyatmano ’rdham patny aste nanvagad virasuh krpi

sah
he
esah
certainly
bhagavan
lord
dronah
Dronacarya
praja-rupena
in the form of his son Asvatthama
vartate
is existing
tasya
his
atmanah
of the body
ardham
half
patni
wife
aste
living
na
not
anvagat
undertook
virasuh
having the son present
krpi
the sister of Krpacarya.

He (Dronacarya) is certainly still existing, being represented by his son. His wife Krpi did not undergo a sati with him because she had a son.