Summary of answer:
Praise be to Allah
The wedding feast (waleemah) may be done by offering any kind of food to those who attend, even if it is made of barley.
In al-Mawsoo‘ah al-Fiqhiyyah (45/250) it says:
The Hanafi, Maaliki, Shaafa‘i and Hanbali fuqaha’ are of the view that there is no minimum requirement for the wedding feast, and the sunnah (of offering a wedding feast) may be fulfilled by offering any kind of food, even if it is two mudds of barley, because of the saheeh hadith: The Prophet (blessings and peace of Allah be upon him) gave a wedding feast of two mudds of barley when he married one of his wives.
‘Iyaad stated that there was scholarly consensus on the fact that there is no minimum requirement for the wedding feast, and that whatever food is offered, the sunnah is fulfilled.
The Shaafa‘is said: The minimum requirement for the wedding feast, in the case of one who can afford it, is a sheep; for others it is whatever they can afford. That is because of the report which says that the Prophet (blessings and peace of Allah be upon him) said to ‘Abd ar-Rahmaan ibn ‘Awf when he got married: “Give a wedding feast, even if it is with a sheep.”
An-Nashaa’i said: What is meant is that the minimum for one who wants to offer a proper feast is a sheep, because it is says in at-Tanbeeh: Whatever food is offered as a wedding feast, it is acceptable. That includes food and drinks that are made at the time of doing the marriage contract, such as sweets and other kinds of food, even if the man is well off.
A number of Hanbalis stated that it is recommended (mustahabb) that the wedding feast be no less than a sheep.
Az-Zarkashi said: The Prophet (blessings and peace of Allah be upon him) said, “… even if it is with a sheep”, and the mention of a sheep here – and Allah knows best – refers to a small amount; in other words, even with something small, like a sheep.
Al-Mirdaawi said: From this it may be understood that it is permissible to offer a wedding feast with less than a sheep, and from the first hadith it may be understood that one may offer more than a sheep, because he regarded that as being little. End quote.
With regard to the udhiyah, one-seventh of a camel or one-seventh of a cow is acceptable, as has been explained previously in the answer to question no. 45757.
It is permissible to buy a share in a cow or camel, even if some of the participants do not intend to offer an udhiyah; rather they want the meat for a wedding feast, or to eat it, or sell it, and so on.
An-Nawawi (may Allah have mercy on him) said in al-Majmoo‘ (8/372): It is permissible for seven people to share a camel or cow for the udhiyah, whether all the participants are members of one household or otherwise, or some of them simply want the meat; that is acceptable on the part of one who wants to offer a sacrifice, and this applies whether it is a sacrifice in fulfilment of a vow, or a voluntary sacrifice. This is our view, and it was the view of Ahmad and the majority of scholars. End quote.
Ibn Qudaamah (may Allah have mercy on him) said in al-Mughni (13/363): A camel is acceptable on behalf of seven people, as is a cow. This is the view of most of the scholars. Then he quoted some hadiths which support that view, then said:
As this is proven, then it makes no difference whether the participants are members of one family or otherwise, or whether the sacrifice is obligatory or voluntary, or whether some of them intend to offer a sacrifice and others simply want the meat, because each of them is only accountable for his share, and the intention of others has no impact on that. End quote.