It's obviously the meaning of online writing, the blogiverse, and everything (because of the issue number: https://github.com/samwilson/twyne/issues/42 ) — so I've added support for "syndications" to Twyne. Each post can have a list of URLS (with labels) at which the post is duplicated. This is the first stage to making Twitter and Flickr imports work, so that each post can point back to where it came from (although, the import process will switch things around and pretend that the posts originate on my own site, even though that's not stricktly the case). Hopefully this will work.
It seems like it's also going to possible to use Twyne's syndications to post to indieweb.xyz — https://indieweb.xyz/howto/en