I think all the characters mentioned by Charlie in Audrey's scene as well as all the characters we see having exchanges at the Roadhouse and then never see again are this season's "Invitation to Love". Their (mostly offscreen) plot and dialogue mirrors the events of the season (most obviously the girl with the rotting arm) with the added complication that they seem to interact with the main plot in some ways (the stolen truck). I think it will all make sense in the Twin Peaks Rewatch Rewatch.
The final episode of Twin Peaks Season 3's description is "What is your name?". I would advise everyone to prepare themselves for a total absence of the original Dale Cooper from the season until the final episode.