According to Halacha, is it permissible for a Jewish woman who is a Mamzer to donate her eggs to help a non-Mamzer Jewish woman who is infertile? Or no, because Mamzerim are prohibited from “entering the congregation of Israel” would it be prohibited? If permissible, would the children be mamzerim or no?

Many Jews practice Shalom Zachar which is a Seudat Mitzvah for new born baby boys (the origin is Talmud saying Jews know the Torah in the womb but lose its knowledge after birth). My question is should they do it if a baby is born from Caesarean section? Or does it make no difference, unlike other aspects of Halacha where it would? The reason I ask is because of the Talmud’s use of the word “emergence” which in other Halacha contingent on childbirth is interpreted as natural birth.