I'm sorry to bother you but I need some help with my heavy heart.
A few months earlier, I had a miscarriage on hospital premises so we were not allowed to bring home the miscarried foetus, and had to arrange a proper funeral. By mistake this was arranged in a non-Muslim graveyard. We didn't know it was unlawful to bury in such a place. Please help me and guide me to what we should do now. Was this a major sin?

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. A child is considered a Muslim according to the religion of his father or parents. Therefore, if he dies he/she should be buried in the graveyard of Muslims not in the graveyard of non-Muslims. In addition, majority of Muslim scholars are of the opinion that if a pregnant wife of a Muslim husband dies and she is a Jew or Christian then she should be buried in the graveyard of Muslims. The back of such a woman should be put facing Qiblah so that the face of the fetus faces Qiblah too since the fetus is considered a Muslim. All the above details are enforced after the soul was breathed in the fetus, before the soul is breathed in it, is considered a part of the body of the woman. The soul is breathed after 120 after the beginning of pregnancy. If you had buried the child in a non-Muslim graveyard after the soul had already been breathed in it then you had neglected the right of your fetus. However, if the matter was out of your ability then you will not be blamed for it. As long as the case happened due to the lack of knowledge, you will not be held responsible for that Insha Allah. Now do not try to move the corpse to another place since doing so after the changing the body of a Muslim is not allowed. However, if the age of the fetus was less than 120 days then there is no harm at all. Allah knows best.