H4 Biometrics Appointment - Passport is in renewal process

Hello, Since my son’s passport had expired, we have applied for the renewal of the passport and it is currently under process with the Indian embassy. In the meantime my son has received his H4 Biometric appointment on 22nd February. I understand that either a passport or state ID is required for the biometric. He does not have a state ID. Is there any other document that my son can use for the Biometric appointment. Or we need to reschedule?