Question: Was miss Ganush alive when she first attacked Christine, or was that the first manifestation and torment of the Lamia? The attack and it's effects seem highly consistent with what happens to Christine later on, and the frail old lady is just too powerful and durable for someone who dies a day or two later.
Question: Christine needs $10,000 for a dangerous seance, so she goes to the shed to gather up some items to pawn, whereupon she again encounters Lamia (as Mrs. Ganush). Christine uses her ice skate to slash a rope that conveniently drops a 100-lb blacksmith's anvil on the demon's head. After the demon vanishes, the anvil, rope and chain are seen on the floor where they fell, so it wasn't just a fantasy sequence. Why does petite little Christine Brown (or anybody, for that matter) have a 100-lb blacksmith's anvil suspended 8 feet in the air with rope and chain out in the shed?
Answer: Because it's a film and Sam Raimi obviously thought it was funny. But I did also wonder.
Answer: Christine didn't get cursed until the end of that fight, so it could not have been the first attack from the Lamia.