Our family knows that Annabel rarely calls her sister by her proper name. Instead she calls her "sister friend". I do not know why she has started this, she knows Cailin's name but chooses not to used it. The girls have a special bond. I think they realize early in their lives that they are not only sisters, but also friends. I pray this love for each other and closeness remains throughout their lives. As someone who did not have a sister, I am so amazed by their closeness and relationship even at such an early age! They will always be SISTER FRIENDS!