Marsha Bailey was a Vault resident during the experiments inside Vault 22. Both her and Elizabeth Bailey were of unknown relation to Dr. Bailey, though it is suggested that they were his wife and daughter. Marsha was observed by Dr. Bailey during her illness inside the common area.
Marsha Bailey was part of the 2nd batch of people infected by the spores from one of Vault 22's experiments. She most likely became a spore carrier.
Marsha Bailey is only mentioned in Fallout: New Vegas.