Is it lawful to bury unborn babies (feotus) in a non-Muslim graveyard?

Praise be to Allah, the Lord of the Worlds; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions. If the parents of these dead fetuses (or one of the parents) are Muslims, then it is unlawful to bury them in non-Muslims graveyards. But if it is certain that their parents are disbelievers, then the dead fetuses should not be buried in Muslim graveyards. Rather they should be buried in disbelievers' graveyards. Allah knows best.