But then I just noticed this little note at Erin McCarthy's website here (how long has it been there?), and to quote everything:
A note from Erin:
Thanks so much for all the interest in reading stories for Allison and Caroline, the two other roommates in The Pregnancy Test and You Don't Know Jack. While I originally intended to write books for them, a change in publishers has made this impossible at the moment. Hopefully some day soon I'll be able to write a 'Happily Ever After' for Allison and Caroline!
I can wait. But please don't say never.