One sacrifice is sufficient on behalf of the members of a household even if they are one hundred strong
Question

                Is one sacrifice sufficient on behalf of all the members of a household, even if they are many?.
Praise be to Allah.One sacrifice is 
    sufficient on behalf of all the members of a household, no matter how many 
    of them there are.  

    Al-Tirmidhi (1505) narrated that ‘Ata’ ibn Yassaar said: I 
    asked Abu Ayyoob: How was the sacrifice done at the time of the Messenger of 
    Allaah  (peace and blessings of Allaah be upon him)? He said: A man 
    would offer a sheep on behalf of himself and the members of his family, and 
    they would eat some and feed others with some.” Classed as saheeh by 
    al-Albaani in Saheeh al-Tirmidhi. 

    It says in Tuhfat al-Ahwadhi: 
This hadeeth clearly 
    states that a single sheep is sufficient on behalf of a man and the members 
    of his household, even if they are many, and that is correct. 

    Al-Haafiz ibn al-Qayyim said in Zaad al-Ma’aad: The 
    teaching of the Prophet  (peace and blessings of Allaah be upon him) was 
    that a sheep is sufficient on behalf of a man and the members of his 
    household, even if they are many in number.  

    Al-Shawkaani said in Nayl al-Awtaar: In fact a single 
    sheep is sufficient on behalf of the members of a household, even if there 
    are one hundred or more, as is indicated by the Sunnah. End quote. 

    Shaykh Ibn ‘Uthaymeen said in al-Sharh al-Mumti’ 
    (5/275): 

    There is no limit to how many people may share in the reward. 
    The Prophet  (peace and blessings of Allaah be upon him) offered a 
    sacrifice on behalf of his entire ummah, and a man may offer a single sheep 
    on behalf of himself and the members of his household, even if they are one 
    hundred strong. End quote. 

    The Standing Committee was asked: There are twenty-two people 
    in this family, and they have one income and one budget. On Eid al-Adha they 
    offer a single sacrifice, and I do not know whether that is sufficient or 
    whether they should offer two sacrifices? 

    They replied: 

    If the family is big but they live in one house, one 
    sacrifice is sufficient for them, but if they offer more than one sacrifice, 
    that is better. End quote. 

    Fataawa al-Lajnah al-Daa’imah, 
    11/408.