These two acting and singing celebs are so close, big sis Haylie even wrote the song "My Sister and I," crooning, "It's my sister and I / We ride side by side / In a corvette / Or a sports car...My sister and I / Sisters sisters forever." Too cute! Hil has also gushed, "My sister and I are best friends and we get along so well. She is so talented and inspiring to me. She's my role model." All together now: Awww.