Two Equals

Half-breed vampire Sarah has married her other half, William, and is now the mother of three-year-old twins with power that defies explanation. Aseret, the demon lord of the underworld, views the twins as a threat to his taking over the world. Sarah, William, and their shapeshifter friends must train the supernatural kids to prepare them for an inevitable encounter against Aseret. For Sarah, training isn't enough and she relinquishes her body to a witch-the one who stole it before. Roaming the underworld as a ghost, Sarah searches hoping to find Aseret's accomplice before Aseret kidnaps, or worse, kills her children.
But reconnecting to her body may be more difficult than Sarah expected. After all, there's only space for one soul in a body, and they're one body short.