All perfect praise be to Allah, The Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad is His slave and Messenger.
If the organizers of the project have appointed a sheep for every person, then it is not permissible for a person who had given money for the sacrifice to take the sheep of other people because this is consuming people's money; rather, he should take a sheep that is slaughtered as a sacrificial animal in his name.
What some people who were entrusted by others do is wrong regarding the slaughter of sacrificial animals, because they buy sheep and slaughter them without designating which sheep is for whom; and the scholars mentioned that this is not sufficient (acceptable).
Shaykh Ibn 'Uthaymeen said:
“They buy herds of sheep and slaughter them on behalf of the people who gave them money to do so. This means that one sheep is sufficient for how many people? For thousands of unknown people; each sheep is sufficient for thousands of unspecified people; they made it for an unknown person, as if it is a pile of food which they take and give in charity, and this is not sufficient (acceptable) in principle, this is not sufficient.
Therefore, the people who are appointed and who receive the money to slaughter on behalf of other people should make a list of the names of the people and then open the list and say: come, the sheep is here: this sheep is on behalf of so and so, Bismillah I slaughter; this sheep is on behalf of so and so; this sheep is on behalf of so and so; this must be done, otherwise they would slaughter one sheep on behalf of thousands of people, while a camel is only sufficient for seven people.”
Shaykh Ibn 'Uthaymeen also said:
“The Udhhiyah must be specified (for whom it is); this Udhhiyah is for so and so, otherwise it is not valid, it is not valid that you gather 100 sheep, slaughter in the name of Allah, slaughter, slaughter! For whom? If we presume that 100 people give you money and you slaughter the first sheep, for whom are you going to intend it; is it for the last one or the first one, while they do not know who is the first and who is the last, so they slaughter for someone unknown; they do not know who he is; so the matter is very serious…”
Allah knows best.