Oh,so you have to breed a vampire with an imaginary friend in hopes of getting a vampire IF hybrid because an IF turned real cannot be turned into a vampire. How about a child of an imaginary friend can they be turned.
Edit. I did it I got a vampire imaginary friend ghost. This is how I did it. I already had the child of an imaginary friend turned real in game so I mated her with Hank Goddard who is a vampire. Then I had them both use the ghost potion so they were ghosts when trying for baby. They eventually had twin girls Scarlet and Violet. Scarlet is a imaginary friend ghost but Violet hit the jackpot and is a vampire imaginary friend ghost.
This is Violet in doll form waiting for her sister to age up. I can try and upload her to the swop shop if anyone wants her. At the moment she is in the child life stage.