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

Plural marriage and fair treatment of co-wives, Dought & clear, - * He has two wives and he is not dividing his time among them fairly

Is it obligatory for a husband with two wives to designate specified
days for each wife. Also, is it permissable that he share the days
between the two. My husband presently has no designated days for us.
He comes to my home when he has finish his rounds at my co-wives
house. He then comes to my home to go to bed. This arrangement is
not acceptable to me. Were on the brink of divorce.
Praise be to Allaah.
The one who has more than one wife has to treat all his wives fairly.
One of the matters in which he must be fair is the division of his
time, i.e., he must give each wife a day and a night, and he must stay
with her on that night.
Al-Shaafa'i (may Allaah have mercy on him) said: "The Sunnah of the
Messenger of Allaah (peace and blessings of Allaah be upon him) and
the opinion of the majority of Muslim scholars indicate that a man has
to divide his days and nights between his wives [giving each a full
day and night], and that he has to be fair in doing so. (al-Umm,
5/158). And he said: I do not know of any (scholarly) disagreement
with the view that a man must share his time among his wives and do so
fairly. (al-Umm, 5/280).
Al-Baghawi (may Allaah have mercy on him) said: If a man has more than
one wife, he has to treat them equally, if they are free [i.e., not
slaves], whether they are Muslims or from among the People of the Book
[i.e., Jewish or Christian]. If he does not treat them equally, then
he has disobeyed Allaah and he has to make it up to the one whom he
wronged. It was narrated from Abu Hurayrah that the Prophet (peace and
blessings of Allaah be upon him) said: "Whoever has two wives and
leans towards (i.e. favours) one of them (over the other), will come
on the Day of Resurrection with half of his body leaning." However
there is some dispute concerning its isnaad. (Narrated by Abu Dawood,
2/242; al-Tirmidhi, 3/447; al-Nasaa'i, 7/64; Ibn Maajah, 1/633;
classed as saheeh by al-Haafiz inBuloogh al-Maraam, 3/310, and
al-Albaani inIrwaa' al-Ghaleel, 7/80).
What is meant by this "leaning" is favouring in terms of actions; a
man will not be taken to task for the inclination of his heart if he
treats (his wives) equally in practical terms. Allaah says
(interpretation of the meaning):
"You will never be able to do perfect justice between wives even if it
is your ardent desire, so do not incline too much to one of them…"
[al-Nisaa' 4:129]
What this means is that you will never be able to treat them equally
in your heart, so do not incline too much towards one of them, i.e.,
do not make your actions follow your whims and desires.
(Sharh al-Sunnah, 9/150-151)
Ibn Hazam (may Allaah have mercy on him) said: Treating co-wives
equally is obligatory, most of all sharing one's nights between them.
(al-Muhalla, 9/175)
Shaykh al-Islam Ibn Taymiyah (may Allaah have mercy on him) said: He
has to treat his wives fairly according to the consensus of the
Muslims. In the fourSunansit was narrated from Abu Hurayrah that the
Prophet (peace and blessings of Allaah be upon him) said: "Whoever has
two wives…" He has to be fair in his division of time between them. So
if he stays with one of them for one night, or two or three, he should
stay with the other for the same number of nights, and he should not
give preference to one of them in his sharing of his time.
(Majmoo' al-Fataawa, 32/269)
Al-'Ayni said, commenting on the hadeeth, "Whoever has two wives…": It
was said that what was meant was that half of his body would be
leaning in a real sense, or that he would have no acceptable excuse
for favouring one wife over the other. The apparent meaning is that
this is in the real sense. This is indicated by the report of Abu
Dawood, "with half of his body leaning." The punishment fits the
crime, because he did not treat them fairly or he deviated from what
is right. Because of his being unfair and favouring one of them, his
punishment is that he will come before the witnesses on the Day of
Resurrection with one half of his body leaning.
('Umdat al-Qaari', 20/199. See alsoal-Mabsoot, 5/217).
Al-Shawkaani also understood this to mean that it is obligatory (to
treat co-wives fairly). Seeal-Sayl al-Jiwaar, 2/301;Nayl al-Awtaar,
6/216
Ibn Qudaamah al-Maqdisi (may Allaah have mercy on him) said: We know
of no dispute among the scholars concerning the fact that it is
obligatory to treat co-wives equally when sharing one's time between
them. Allaah says (interpretation of the meaning):"and live with them
honourably" [al-Nisaa' 4:19], but favouring one of them is not
honourable.
Al-Mughni, 8/138
This husband has to fear Allaah and be fair in his division of his
time. The wife has to tell him of the ruling of sharee'ah concerning
what he is doing, and of the warning of mistreatment. She should
remind him of Allaah and the Hereafter, so that he will check himself
and be fair in his division of time. This is better than separating,
in sha Allah. And Allaah knows best.