Whenever any family grows, it's an exciting moment for its current members. But these girls are beyond elated when they find out they're going to have a new sibling. When their mom announces she's pregnant by surprising them with two custom cookie cakes that read "Big Sister" and "Big Sister...Again," the two erupt in adorable delight. Watching them look at the sonogram picture -- and embrace one another in happiness -- is so heartwarming.