Can one Person use a cow or camel for Udhiyah

It is permissible for seven people to share a cow for Udhiyah. If it is permissible for seven to share a single cow, then it is even more permissible for fewer than seven to share it, with the additional share being voluntary, just as if one person were to slaughter a cow for Udhiyah, even though a sheep would suffice.

Imaam ash- Shaafi'ee (may Allaah have mercy on him) said: 'If they are less than seven, it suffices them, and they are considered to be giving the extra portion as charity, just as a camel suffices for someone obligated to give asheep, and they are considered to be giving the extra portion as charity instead of of the sheep.' (Al-Umm, 2/244)

Al-Kasaanee said:  'There is nodoubtabout the permissibility of sacrificing a camel oracow for fewer than seven people, whether two, three, four, five, or six share in acamel or a cow; becausesince seventh is permissible, then more is even more so. It makes no difference whether the shares are equal in quantity or different, such that one of them gets half while the other gets a third, and the other gets a sixth, provided that it does not fall below seventh.' (Badaa' as-Sanaa' 5/71).