Does the divorced mother's marriage invalidate her right to her child's custody, especially since the father is married?

The mother has a greater right to the custody of her child as long as she does not marry. If she marries, then the maternal grandmother has a greater right to the custody. If the maternal grandmother is not alive or waives her right, then the right transfers to the father, and there is no difference whether he is married or not. This is in the case of a dispute. However, if the rightful custodian agrees to the child remaining with the mother after her marriage, then there is no harm. As for the financial support, it is the father's responsibility, whether the child is with the mother or someone else.