We use the plugin Redirection by John Godley, where we manually designate redirects for a site.
On one such site, due to major architectural changes, we installed this plugin as well. Our plan was to attempt to auto-generate those redirects we didn’t already know about, then move them from 404 Solution into Redirection via export/import. That way we’d maintain all redirects in a single consistent location, using a tool that has proven successful for us.
Do you know in what order the plugins will evaluate a given request? Will Redirection evaluate before 404 Solution? Or will 404 Solution attempt to auto-redirect URLs we’ve already addressed in Redirection?