The producers knew she was pregnant, so they were going to reveal her origins before leaving the show to have the baby, but she ended up leaving early due to complications. Would she have played a character in the 1897 flashback?
Weren't Alexandras' origins revealed in the early part of the series, before the introduction of Barnabus?! She started her first appearance as an orphan at the foundling home, correct?!
Apparently after Joan Bennett mistook Alexandra Moltke for one of her own daughters from a distance when she first saw her, Victoria was intended to be Elizabeth's daughter. The play Return to Collinwood (approved by Dan Curtis) confirmed this, but who Victoria's father was remains anyone's guess...