英语写信格式时的称呼,是首字母大写还是全部首字母大写呢?

1."Dear students; Dear teachers; Dear parents..." 仅第一个字母大写.
2.我的家人有我的父母们和我的妹妹和弟弟:
(a) My family members are my parents,a sister and a brother.
(b) There are five members in my family:Myself,my parents,a (younger) sister and a (younger) brother.