How can files be added to an existing zip archive?

[dca00]

Samples show only how to create a brand-new ZIP and to add one file. How can we add more than one to a file that already exists?

[SourceproStudio]

这是来自QQ邮箱的假期自动回复邮件。   您好，我最近正在休假中，无法亲自回复您的邮件。我将在假期结束后，尽快给您回复。