@BillSeitz @holden @WardCunningham IndieWeb approach:
1 reply from your own site
2 POSSE e.g. Twitter
3 webmention to posts on indieweb sites which then copy and embed such a reply inline under the post.
Already works when received by these "BlogComment" engines for example:
* Known / withknown.com
* WordPress Webmention Plugin / https://indiewebcamp.com/Getting_Started_on_WordPress
For more see: