Justice between wives is only condition for taking more than one wife
19-1-2016 | IslamWeb
Question:
My older sister got married more than 20 years ago. My older brother arranged the marriage for his best friend's wife's brother. My sister and her husband tried to have children for eight years and tried treatments to cure her infertility. However, the doctors said she will never be able to conceive. So her husband asked her and our family if he could remarry to have children. We consented. We also gave money from our late father's estate in her share of inheritance so that our sister could have her own house to have security after her husband's remarriage. When her husband remarried, he kept his new wife and kids from her in the same house. Both he and our sister are equal owners of that house. Now the problem is that our other youngest sister has been widowed with a ten-year-old son, ever since his birth. Now my brother's best friend, a wealthy married old man, who is the same man through whom we arranged the marriage of our older sister, has been asked by us, the brothers, to marry our younger widowed sister. We are facing opposition from our older sister's husband and his family. The same one who remarried for children. They are against it because the first wife of my brother's friend is the sister of my older sister's husband. They say that they took our consent for their son's remarriage and that their son had a reason to marry a second wife (to have children). They say that our younger sister's suitor has no reason to remarry. However, from our understanding, neither consent nor reason is required. Our mother also opposes this proposal because she thinks that our intentions are to get revenge from our brother-in-law who remarried. Is it not hypocritical for him to oppose his sister's husband's marriage to our sister when he himself remarried while having our sister as his wife. What should we do? Can we marry off the younger widowed sister despite all the opposition that we face? We feel that our sister will have a good life if she remarried a wealthy man who would also accept her child.
Answer:
All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah and that Muhammad 
is His slave and Messenger.
If the man who proposed to marry your widowed sister is religious and has a good moral character and your sister is pleased with him as a husband, then you should marry her off to him. The Prophet, sallallaahu ‘alayhi wa sallam, said, “If a man whose religion and moral conduct are pleasing to you proposes to you, then let him marry; otherwise there will be great mischief and corruption on earth.” [At-Tirmithi and Ibn Maajah]
There is no consideration about what you mentioned regarding the matter of seeking permission, or that the purpose of this marriage is to take revenge and so forth. Allaah only conditioned justice between the wives when marrying more than one wife, as we have already highlighted in fataawa 86818 and 81469.
Please also refer to fatwa 84411 for more benefit.
On the other hand, it is not an obligation to obey the mother in all what she orders; all this is restricted to matters that are permissible and reasonable only. Indeed, it is not at all permissible or reasonable for her to prevent her daughter from marrying without a sound reason.
For more benefit on the limits of obedience to parents, please refer to fatwa 131695.
Allaah knows best.