From The Heretic Knowledge Vault
She shares a house with Nikki, whom she inconsiderately sends out for carrots the first time we see her -- "inconsiderately" because Nikki is a vampire, she's sent out in full daylight, and exposure to the sun would do to Nikki what exposure to sun does to vampires. Why doesn't Becky go herself? Good question, but given the way the neighborhood is (Naga and Fran also live nearby, after all), there's a pretty good chance she's got some manner of weirdness herself that's incompatible with a casual trip to the store. (Then again, being snack food for a vampire is probably weird enough even if there's nothing else peculiar about her.)
Her sister Sarah has been named in the strip, but not seen yet.