Edit: See
main post. As promised, here's the OFB only versions of the base game subhoods:
(Links removed.)
I also fixed Riverblossom Hills (main hood and subhood) so that the neighbourhood pictures show up correctly, and a couple of memories as well.
(Links removed.)
And! I succeeded in making Belladonna Cove into a Downtown! Put it in the same folder as the regular downtown template.
A couple of notes about it: It DOES require Mansion & Garden Stuff, and I've had to move out all the families in apartments, because merging in a subhood breaks families that live in apartments. You can move them right back into their homes, though. I think there's a debug option to rent the apartment furnished. Pescado's apartment hack also makes renting furnished into a default option.
(Link removed.)
I'll update the main post with these links later.