This is gonna be a weird answer. They are not connected but they are connected. Now for the explanation.
Plunge is not connected to Basketful of Heads or Daphne Byrne or Dollhouse Family. However, there is a back story that is connected. @hashtag-goodtobejo at the Black Label society has made a reading order for Sea Dogs.
We are not really focusing on that story in the House of Horror as we have been focusing on separate titles by themselves and not in release date reading order.