This is an idea that was mentioned in #1278 and could be part of the #1839 meta-issue...
So the idea is basically to have an additional "Place in layout" action available in the drop-button in the "Operations" column (mockup):
...this would pop up a dialog asking which layout to add the block to, and upon selecting a layout, would redirect to the "Manage blocks" page for the selected layout, perhaps with a "Select region" prompt?
GitHub Issue #:
3406
Recent comments
You can use Rules or the Node Notify module for comments. When a new account is created, I believe there are Rules to send.
Email notifications
There's a few way to accomplish it, but it really depends on your full requirements. I'm working on a contact management module but it won't be released for a few months. There...
Pairing fields
I'm fairly sure that some people have done this successfully in Backdrop. Please can you list the modules you are using; that should help us get the right people to join this conversation.
How to render facet blocks?