When Scarlett learns of the blood vial from her mother, she said she got it from her grandmother (Scarlett's great grandmother). She is shown as an old woman giving the vial to a young Abigail. Since Dmitri revealed that Abraham Van Helsing was Vanessa and Scarlett's great great great grandfather, this means that Lillian could only have been his daughter, not his granddaughter as Siobhan says she is, since Lillian died young and thus could not have been the old woman shown to be Vanessa and Scarlett's great grandmother, who would have been Abraham's granddaughter.