Plural marriage and fair treatment of co-wives, Dought & clear, - * A wife giving up her right to maintenance; and is the first wife’s approval needed before one can marry a second wife?

Is it halal to have a second wife who says she does not need financial
support. If so, what if the first wife does not allow the
marriage..can a man still get married again?
Praise be to Allaah.
Maintenance is one of the rights of the wife which is an obligation
upon her husband. Allaah says (interpretation of the meaning):
"Men are the protectors and maintainers of women, because Allaah has
made one of them to excel the other, and because they spend (to
support them) from their means."
[al-Nisaa' 4:34]
If the woman foregoes this right, to which she is entitled – which is
her maintenance– then it is no longer obligatory upon her husband.
Ibn Qudaamah said: If she agrees to forego some part of her share (of
her husband's time) or her maintenance, or all of that, this is
permissible. (al-Mughni, vol. 7, p. 244).
With regard to the permission and approval of the first wife for a
plural marriage, this is not a condition and the husband does not have
to seek the permission of his first wife to marry a second. But it is
prescribed for him to be kind to her and to spend money and to say
kind words so as to calm her down and reduce her jealousy. The
Standing Committee was asked about the first wife's approval for one
who wants to marry another wife. Their response was:
It is not obligatory for the husband, if he wants to take a second
wife, to have the approval of the first wife, but it is the matter of
good manners and kind treatment that he should speak to her kindly in
such a way as to reduce the feelings of hurt which are natural in
women in such cases. That is by smiling at her, showing that he is
happy to see her, being kind, speaking nicely and by spending money on
her if necessary.
SeeFataawa Islamiyyah, vol. 3, p. 204