It is permissible to share in the sacrifice, and a camel or a cow is sufficient for seven people Sahih Muslim 1318 c
Arabic hadith text
وَحَدَّثَنِي مُحَمَّدُ بْنُ حَاتِمٍ، حَدَّثَنَا وَكِيعٌ، حَدَّثَنَا عَزْرَةُ بْنُ ثَابِتٍ، عَنْ أَبِي الزُّبَيْرِ، عَنْ جَابِرِ بْنِ عَبْدِ اللَّهِ، قَالَحَجَجْنَا مَعَ رَسُولِ اللَّهِ صلى الله عليه وسلم فَنَحَرْنَا الْبَعِيرَ عَنْ سَبْعَةٍ وَالْبَقَرَةَ عَنْ سَبْعَةٍ .
Translation
Jabir b. 'Abdullah (Allah be pleased with him) reported
We performed Hajj along with Allah's Messenger (ﷺ), and we sacrificed a camel on behalf of seven persons, and a cow on behalf of seven persons.