"Forniphilia" means "human furniture". The people listed here have inanimate versions of themselves, allowing you to put them in various places of your house.
You can see their transformation dialogue on the slave chatter page.
Except for Sarah and Victoria, each character has two different ones, depending on if you use the Stone Skin spell.
Brktnye: Bottle holder/Cooler (holds the bottle between her breasts, Mindless form)
Eric: Statue/Stone Statue (topless, Normal form)
Jane: Foot rest/Rubber foot rest (Slut form)
Ms. Rack: Pretty literally a rack/wooden rack (Mindless form)
Sarah: Doll (Any form, though making her a doll renders all forms identical to Normal.) Requires to complete a minor sidequest.
Victoria: Sleep mode (Robot form).