@rob-brown said in Is there any way to use this with an existing userbase?:
Thanks. Is it fair to say that there isn't any existing plug in that does any or this? (or anything that provides a starting point?)
There are some plugins that might help IF you are using a standard API. But there is no possibility of having a plugin that does this universally.
For example, if you wanted NodeBB to do this with generic WordPress, you'd need a very specific plugin for that. If you also or alternatively wanted to do it with Drupal, you'd need a different plugin. Every application backend would need a unique plugin.
So outside of using things like open universal authentication APIs, there can't be a pre-existing plugin, you'd need one for your specific use case.