Bloggerではﾗﾍﾞﾙによって分けるしか無いようです｡

投稿にﾗﾍﾞﾙを付けるにはどうすればよいですか｡ - Blogger ﾍﾙﾌﾟ

ﾁｰﾑ ﾌﾞﾛｸﾞの場合は､各ﾒﾝﾊﾞｰが名前やﾆｯｸﾈｰﾑなど独自のﾗﾍﾞﾙを付けてﾒﾝﾊﾞｰ別に投稿を読むことができます｡ この他にも新しい使い方があります｡ぜひお気軽にお試しください｡

Sorting posts by author - Blogger Help

Use labels to do something similar. If each author would label his posts with his name, then you could have a labels list just for the authors' names. Clicking the label would display all the posts of that author.