Is she sinning by attending wedding parties that involve reprehensible things if she sits far away and helps them with cooking etc?
Question

                The wedding parties in our country include drums, singing and dancing. Is there any sin on me if I go to the party and sit far away from where the singing is taking place, especially at weddings of my husband’s family and my family, where I can’t not go and help with permissible things such as cooking etc?.
Praise be to Allah.
    Firstly: 

    It is not permissible to attend wedding parties that include 
    reprehensible things such as singing accompanied by drums or other musical 
    instruments, apart from the daff, or mixing between men and women, or other 
    evils, except for one who is able to denounce that and thinks it most likely 
    that he will be able to put a stop to the evil by denouncing it. 

    Ibn Qudaamah (may Allaah have mercy on him) said: If a person 
    is invited to a waleemah in which there is sin, such as alcohol and musical 
    instruments, etc, and he can denounce it and put an end to the evil, then he 
    must attend and denounce it, because then he will be fulfilling two 
    obligations: accepting the invitation of his Muslim brother and putting a 
    stop to evil. But if he is unable to denounce it, then he should not attend. 
    If he does not know of the evil until he gets there, then he should put a 
    stop to it, and if he is not able to, then he should leave. Something 
    similar to this was said by al-Shaafa’i. End quote from al-Mughni, 
    7/214. 

    It says in Fataawa al-Lajnah al-Daa’imah: If the 
    wedding party is free of evils such as mixing between men and women, 
    promiscuous singing and so on, or if she attends she will be able to change 
    the evils, then it is permissible for her to attend in order to share in the 
    joy. Rather attendance is obligatory if there is some evil that she is able 
    to put a stop to. 

    But if the party involves evils that she cannot denounce, 
    then it is haraam for her to attend, because of the general meaning of the 
    verses in which Allaah says (interpretation of the meaning): 

    “And leave alone those who take their religion as play and 
    amusement, and whom the life of this world has deceived. But remind (them) 
    with it (the Qur’aan) lest a person be given up to destruction for that 
    which he has earned, when he will find for himself no protector or 
    intercessor besides Allaah”

    [al-An’aam 6:70]  

    “And of mankind is he who purchases idle talks (i.e. 
    music, singing) to mislead (men) from the path of Allaah without knowledge, 
    and takes it (the path of Allaah, or the Verses of the Qur’aan) by way of 
    mockery. For such there will be a humiliating torment (in the Hell‑fire)”

    [Luqmaan 31:6]
And there are very many 
    ahaadeeth which condemn singing and musical instruments. End quote from 
    Fataawa al-Mar’ah, compiled by Muhammad al-Musnad, p. 92 
Secondly: 
If your going to the 
    wedding and taking part in the cooking etc will not result in your listening 
    to the evils, or approving of them or helping in them, such as if the place 
    where the evil actions are being committed is far away from you, or you will 
    be able to leave before they start the reprehensible actions, then there is 
    nothing wrong with your going in that case, but you should offer them advice 
    and explain to them the rulings on these evils, and tell them that it is 
    haraam to take part in them. 
In his commentary on the 
    verse (interpretation of the meaning):  
“And it has already 
    been revealed to you in the Book (this Qur’aan) that when you hear the 
    Verses of Allaah being denied and mocked at, then sit not with them, until 
    they engage in a talk other than that; (but if you stayed with them) 
    certainly in that case you would be like them. Surely, Allaah will collect 
    the hypocrites and disbelievers all together in Hell”
[al-Nisa’ 4:140]
al-Qurtubi (may Allaah 
    have mercy on him) said: “then sit not with them, until they engage in a 
    talk other than that” means, talk other than kufr; “certainly in that 
    case you would be like them”. This indicates that it is obligatory to 
    avoid those who commit sin if they openly commit an evil action, because 
    whoever does not avoid them is approving of what they are doing, and 
    approving of kufr is itself kufr. Allaah says “certainly in that case you 
    would be like them”. So whoever sits in a gathering where sin is 
    committed and does not denounce it has a burden of sin just like them. 
They should be denounced 
    if they speak of or do sinful things; if a person is not able to denounce 
    them, then he should get up and leave them, so that he will not be one of 
    those mentioned in this verse. End quote. 
Al-Sa’di (may Allaah have 
    mercy on him) said: 
This also includes 
    attending gatherings where sin and immorality take place, where the commands 
    and prohibitions of Allaah are taken lightly and the limits that He has set 
    for His slaves are transgressed. It is forbidden to sit with them “until 
    they engage in a talk other than that”, i.e., other than disbelieving in 
    the verses of Allaah and mocking them. “certainly in that case” 
    means, if you sit with them in those circumstances, “you would be like 
    them” because you have approved of their kufr and mockery of Islam, and 
    the one who approves of a sin is like the one who does it. 
To conclude, the one who 
    attends a gathering in which Allaah is disobeyed is obliged to denounce them 
    if he is able to, or to leave if he is not. End quote. 
Tafseer al-Sa’di, 
    p. 217 
And Allaah knows best.