Some necessary guidelines for collective sacrifice
To participate in the sacrifice of such an animal, it is necessary that all the participants should have the intention of sacrifice only and that all participants should pay the 7th part of the price of the animal. It is better that all of them are present at the time of the buying the animal. However, it is correct if one person buys on behalf of all the 7 persons. The meat of the sacrificed animal should be distributed equally. If even one person participates with the intention of something other than sacrifice, like with the intention of eating meat or doing business with the meat or if even one person does not pay the price properly or if the meat is not distributed properly, then the sacrifice of all the 7 becomes invalid. As mentioned in Fatawa A’alamgiri, Vol. 5, Pg no. 204.
As mentioned in Fatawa A’alamgiri:
(Fatawa A’alamgiri, Vol. 5, Pg. No. 304)
If a single person buys a cow (or some such animal) with the intention of individual sacrifice, then later on includes other people as well, then the sacrifice will be valid, but this is not free of undesirability. Of course, if at the time of buying itself, the intention to include others was present, then there is no undesirability, provided that person is wealthy and sacrificing an animal is Compulsory (Wajib) on that person. As mentioned in Fatawa A’alamgiri:
(Fatawa A’alamgiri, Vol. 5, Pg. No. 304)
All the participants should weigh the meat and distribute it equally and the distribution should not be by estimation. If the head, feet, etc. are also included along with the meat, then one may distribute by estimation as well. As mentioned in Durre Mukhtaar:
(Durre Mukhtaar, Vol. 5, Pg. No. 223)