What happens to children of an annulled marriage is something that needs to be worked out between the two parents and the courts.An annulment is a declaration that a sacramental marriage never happened: the two people were never actually married in the eyes of the Church because certain conditions failed to be met upon entering into the marriage. The purpose of marriage is to bring one’s spouse to heaven and for the bearing and raising of children, a person might consider that if a sacramental marriage did not exist then what about the children? Are the children of an annulled marriage illegitimate?
Legitimacy is a legal concept dealing primarily with inheritance. There is nothing illegitimate about children of an annulled marriage in the eyes of the Church. They can still receive the sacraments, i.e. they can be baptized, receive communion, get married or become a priest, receive confirmation, et cetera.
Canon 1137 of The Code of Canon Law states that “The children conceived or born of a valid or putative marriage are legitimate.” Canon 1061 of the Code of Canon Law states that “An invalid marriage is called putative if it has been celebrated in good faith by at least one of the parties, until both parties become certain of its nullity”. A putative marriage is a marriage in which at least one of the parties considered valid at the time of the marriage even though it was later declared invalid and annulled. Therefore an annulment has no bearing on the status of the legitimacy of the children within the Church.
The only way for invalid children, in the eyes of the church, to be born would be if both parents never thought they were getting married, which is very difficult to occur. As legitimacy is a legal concept rather than moral, it is possible that illegitimate children become rendered canonically legitimate.
So if you have the question about what happens after your parents gets their marriage annulment, do you become illegitimate or not. The answer would be that annulment has no effect on the legitimacy or illegitimacy of kids born from ant particular union. Children either are legitimate or are not, whether there was an annulment or not. Most of the time, children from an annulled marriage are still legitimate.