This does not alter the fact that "adelphos" can be used both expansively and narrowly, and in fact unless the parents are identified, we'll never know by the deisgnation "adelphos" alone if broad kinship, spiritual fellowship, or commonality of parents is referred to.
" unless the parents are identified, we'll never know by the deisgnation "adelphos" alone if broad kinship,"
So we don't know whether Andrew and Peter were brothers or whether Lazarus was the brother of Mary and Martha?