Plural marriage and fair treatment of co-wives, Dought & clear, - * Her co-wife threatens her, is hostile towards her and does not greet her with salaam

What to do when you are married to the same brother and the first wife
threatens you and curses at you and will only give salaams when around
other people to save face but doesn't speak when no one else is
around. Ive been married for 9years to him her longer.
Praise be to Allaah.
She has to bear it with patience as much as possible, and not repay
evil with evil. She should respond to her co-wife's provocations by
keeping silent and keeping calm. If she can write her a letter
expressing her views, this is good. Then after that she will not be
responsible for what she (her co-wife) does, because she will have
done what she is obliged to do.
Shaykh Muhammad al-Duwaysh
Adhere to the words of Allaah (interpretation of the meaning):
"and when the foolish address them (with bad words) they reply back
with mild words of gentleness"[al-Furqaan 25:63]
"Repel (the evil) with one which is better (i.e. Allaah orders the
faithful believers to be patient at the time of anger, and to excuse
those who treat them badly) then verily he, between whom and you there
was enmity, (will become) as though he was a close friend"[Fussilat
41:34]
Know that there is no better way of dealing with her than fearing
Allaah concerning her when disobeys Allaah with regard to you..
And Allaah is the Guide to the straight path.

Plural marriage and fair treatment of co-wives, Dought & clear, - * There is no hadeeth which says thata wife’s permission is required before taking another wife

Is there a hadith that relates to a husband needing the permission of
present wife to marry 2nd wife?
Praise be to Allaah.
There is no hadeeth which states that, and it is not conditional for
the husband to have his wife's permission to take another wife. But it
is in everyone's interests for him to try to get her consent, because
this will help to reduce problems in the marriage.
Shaykh Sa'd al-Humayd