want to do a Heifer gift for extended family, wwyd?

I want to do a Heifer donation for my Dad's side of the family. We usually go to their house for Christmas Eve, but this year we are going to my parents house. I am debating about doing little $20 animals vs. buying one whole animal like a sheep for the entire family. They all see each other on Christmas eve so I could print the card, send it to my aunt and uncle's house, and say do not open until Christmas Eve. The people who we'd be getting the gift for are:
my paternal grandma, my aunt & uncle & 3 cousins (my dad's brother), and my two great aunts (my paternal grandpa's sisters, and one of the aunt's life partner). I first learned about Heifer from one of the aunts who remarked that she gave her accountant, and her step son a cow or a pig one year so it is something they are familiar with.

WWYD?