It is permissible to share in the sacrifice, and a camel or a cow is sufficient for seven people Sahih Muslim 1318 f
Arabic hadith text
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، أَخْبَرَنَا هُشَيْمٌ، عَنْ عَبْدِ الْمَلِكِ، عَنْ عَطَاءٍ، عَنْ جَابِرِ بْنِ، عَبْدِ اللَّهِ قَالَكُنَّا نَتَمَتَّعُ مَعَ رَسُولِ اللَّهِ صلى الله عليه وسلم بِالْعُمْرَةِ فَنَذْبَحُ الْبَقَرَةَ عَنْ سَبْعَةٍ نَشْتَرِكُ فِيهَا .
Translation
Jaibir b. 'Abdullah (Allah be pleased with them) reported
We performed Hajj Tamattu' along with Allah's Messenger (ﷺ) and we slaughtered a cow on behalf of seven persons sharing in it.