All perfect praise be to Allah, The Lord of The Worlds; and may His blessings and peace be upon our Prophet Mohammad.
We believe that in advance authorizing of a trusted entity to slaughter voluntary Hadys and Udhiyahs is permissible; whereas, obligatory Hady in Qiraan and Tamatu` Hajj as well as when restrictions of Ihram are violated, authorizing must be delayed until Hajj takes place and a violation is committed. This is because the first type (voluntary) is permissible even if the person hasn`t performed Hajj while the second type (obligatory) is based on the occurrence of its cause. And Allah Knows Best.