如何通过相关模型订购关系？

Question

考虑以下模型定义：

class Issue(Base):
    id = Column(Integer, primary_key=True)
    timestamp = Column(DateTime)

class Author(Base):
    id = Column(Integer, primary_key=True)

class Article(Base):
    [...]
    issue_id = Column(Integer, ForeignKey('issue.id'))
    issue = relationship('Issue')
    author_id = Column(Integer, ForeignKey('author.id'))
    author = relationship('Author', backref=backref('articles', order_by=<???>))

我希望Author.articles关系（在上面定义为Article.author关系中的backref）由文章排序＆＃39; issue.timestamp。

这可能吗？

BONUS ：如果Article有多个[{1}}模型的外键，会怎样？