Aren't Youki, Layla and Myouren, and Renko canon characters though?
Hakurei miko's a given, though satsuki tecnically never existed though.
TvTropes' definition for "OC Stand-in" is of "a canon character that gets little screentime or few (if any) lines, and therefore can be molded into whoever the fans want". Since every person except Renko didn't even appear in any canon material (only mentioned in the background of other characters in Myouren, Layla and Youki's cases), I think they fit the trope.
TvTropes' definition for "OC Stand-in" is of "a canon character that gets little screentime or few (if any) lines, and therefore can be molded into whoever the fans want". Since every person except Renko didn't even appear in any canon material (only mentioned in the background of other characters in Myouren, Layla and Youki's cases), I think they fit the trope.