I intend to offer udh-hiyah (Eid sacrificial animal) this year on behalf of my parents. Is there something obligatory to be done either by me or by my parents? May Allah reward you!

All perfect praise be to Allah, the Lord of the worlds. I testify that there is none worthy of worship except Allah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and messenger.

It is recommended for your parents, if they are alive, to refrain from cutting anything from their hair or nails from the time when the new moon of Thul-Hijjah is seen until the time of slaughtering. This is based on the hadith that was narrated on the authority of Umm Salamah in which the Messenger of Allah, sallallaahu ‘alayhi wa sallam, said: "When you see the moon of Thul-Hijjah, let anyone of you who intends to offer udh-hiyah not take anything from his hair or nails (until he has offered the sacrifice)." [Muslim]

According to the wording of another narration: "…He should neither remove anything of his hair nor trim his nails."

The scholars indicated that the wisdom behind this command is to keep all the parts of the body intact until they are saved from Hell in full. Cutting anything of one's hair or nails is disliked, as long as there is no need for this. If there is a need to take anything from nails or hair, however, it is no longer disliked.

You are not required to abstain from taking anything from your hair or nails, since you are acting as their delegate, unless you intend to make them share the udh-hiyah with you. In the later case, you are required not to take anything from your hair or nails until the time of slaughtering. Those of whom you intend to let them share in the reward of udh-hiyah from among your family members are not required to do the same.

Allah Knows best.