His country forbids plural marriage and he wants to marry a second wife with the permission of her brother but not her father
Question

                I live in a country where polygamy is prohibited. Customary marriage is not allowed either; so it cannot be registered one day! The wali is not accepting the idea of letting one of his daughters get married secretly. What is the solution for this, knowing that I am married but liked her, and she agreed to marry in such a way? Her younger brother who is 25 years old also agreed, but he requests that we keep this marriage secret.
Praise be to Allah.
    Firstly: 

    We do not know how some of those to whom Allaah has granted 
    authority over the Muslims dare to oppose Allaah and His religion. They are 
    not content only to forego ruling in accordance with that which Allaah has 
    revealed, but they also oppose sharee’ah, go against its rulings and mock 
    it. An example of that is their putting restrictions on that which is halaal 
    and banning it, and spreading haraam and approving of it. If one commits sin 
    and that is limited to himself, the matter is not as serious as one who 
    propagates sin by force of law, so that the one who does it is rewarded and 
    the one who does not do it is punished. We ask Allaah to set the affairs of 
    the Muslims straight, both rulers and subjects. If they were to think for a 
    few moments of how their destiny is a narrow grave in which they will not 
    have their servants, followers, ministers, wealth, crowns, food and drink 
    with them, they would understand this matter and realize that it is serious 
    and there is no room for joking. If they were to think of the meeting with 
    their Lord, they would re-examine the path they have chosen to follow. If 
    Allaah saw anything good in them He would have guided them. 

    Secondly: 

    You should realize that it is not permissible to marry 
    without the woman’s wali (guardian) being involved. If her father is present 
    then her brother has no right to arrange her marriage. The father loses the 
    right of guardianship if it is proven that he is preventing his daughter 
    from marrying anyone, for no legitimate shar’i reason or for no reason that 
    is acceptable according to sharee’ah. If he prevents her from marrying in a 
    case like that which you describe, he has done well, and it is in accordance 
    with sharee’ah and sound reason. How can you want to marry his daughter with 
    no documentation that is recognized by the state?! Do you know of the evil 
    consequences that can result from that? 

    Documentation of marriage contracts – and other kinds of 
    contracts – is not a bid’ah or innovation in Islam, rather it serves the 
    general purposes that are in accordance with sharee’ah.  

    General purposes (al-masaalih al-mursalah) are those which 
    Islam did not refer to in specific terms, so they are not enjoined or 
    ignored. Rulings on these general purposes are to be based on the general 
    principles of sharee’ah.  

    Shaykh al-Islam Ibn Taymiyah (may Allaah have mercy on him) 
    said, defining the meaning of al-masaalih al-mursalah: 

    This applies to cases where the mujtahid thinks that this 
    action will bring a certain benefit and there is nothing in sharee’ah to 
    forbid it. 

    Majmoo’ al-Fataawa (11/342, 
    343). 

    There are several interests to be served by documenting 
    marriage, such as the following: 

    1 – Preserving the wife’s rights, such as proof of the 
    delayed portion of the mahr, recording the conditions stipulated by her, and 
    allowing her to take her share of inheritance from her husband and 
    children. 

    2 – Proof of her children’s parentage from her and their 
    father. 

    3 – Prevention of another marriage contract being done for 
    her when she is married to another husband. 

    4 – Preserving the husband’s rights, as the mahr that the 
    wife received is recorded. 

    5 – Preventing the husband from marrying more than four 
    women. 

    And there are many other interests, which sharee’ah would not 
    overlook, rather it would stipulate them as conditions in marriage so as to 
    preserve people’s rights and ward off evil. 

    In al-Mawsoo’ah al-Fiqhiyyah (6/170) it says: 

    Allaah has prescribed recording and witnessing so as to 
    protect people’s rights. He says (interpretation of the meaning): 

    “O you who believe! When you contract a debt for a fixed 
    period, write it down” 

    “And get two witnesses out of your own men.” 

    “But take witnesses whenever you make a commercial 
    contract”

    [al-Baqarah 2:282]

    And Islam enjoins documenting some commitments because of 
    their seriousness, such as marriage. End quote. 

    The scholars of the Standing Committee were asked: 

    Is it necessary in marriage to have a person who prompts the 
    woman’s wali to give the proposal and prompts the husband to accept, or is 
    the marriage valid without this person if the marriage fulfils all the 
    conditions and necessary aspects? 

    They replied: 

    If the matter is as described in the question, whereby you 
    propose and the father accepts, and there are witnesses, and the girl named 
    in the marriage contract agrees, then the marriage is valid, even if another 
    person does not do the marriage contract between you, because that is not a 
    condition of the marriage being valid or complete. Rather the government 
    requires people to do the marriage contract before one whom it has 
    authorized to do that and record it, so as to avoid chaos and prevent people 
    from toying with marriage, and so as to preserve lineages and protect 
    people’s honour and rights, and so as to avoid denial of prior agreements in 
    the event of disputes. Obeying the authorities in such good matters is 
    obligatory, because that is helping them to run people's affairs properly 
    and serve their best interests. 

    Shaykh Ibraaheem ibn Muhammad Aal al-Shaykh, Shaykh ‘Abd 
    al-Razzaaq ‘Afeefi, Shaykh ‘Abd-Allaah ibn Ghadyaan, Shaykh ‘Abd-Allaah ibn 
    Munay’ 

    Fataawa al-Lajnah al-Daa’imah 
    (18/105, 106) 

    Based on this, the fact that the father of this woman has 
    refused to let you marry her because of the ban on plural marriage is 
    acceptable, and what he has done is not going against sharee’ah, and it is 
    not permissible for you to marry her without her father’s permission. Her 
    brother’s acting as her wali is invalid if her father is present, and any 
    marriage contract that is done with her is invalid and unacceptable. 

    Thirdly: 

    As for the ‘urfi marriage, it takes two forms: 

    1-Where a woman gets married in 
    secret, without the approval of her wali. This is what people think of when 
    this word is used. If that is the case, then it is a haraam contract which 
    is not valid, because the approval of the wali is one of the conditions of a 
    marriage contract being valid.

    2-Marriage with the approval of 
    the wali, but without announcing or publicizing the matter, or documenting 
    it in the courts. Although this is a valid marriage in that it has met the 
    conditions, it leads to many negative consequences, and those scholar who 
    have examined this issue have ruled that it is definitely not allowed, 
    especially because of the lack of documentation. 
    

    In your case which you have asked about here, the woman’s 
    father does not approve of the marriage, so it is not allowed for two 
    reasons: 

    (i)The wali has not given his 
    approval

    (ii)It has not been documented.

    In the answer to question no.
    2127 you will find an 
    important summary of the conditions of marriage and the conditions of the 
    wali. 

    In the answer to question no.
    7989 you will find further 
    important information on the importance of the wali as a condition of the 
    marriage being valid. 

    In the answer to questions no.
    45513 and
    45663 you will find a 
    discussion on the ruling on ‘urfi marriage. 

    And Allaah knows best.