Rosemary West, 40, now faces joint charges with her husband of murdering Carole Ann Cooper, 15, who went missing in Worcester in November, 1973, and Lucy Katherine Partington, 21, who went missing in December the same year in Cheltenham, Gloucestershire.
Mrs West was in court in Gloucester on Monday jointly accused with her husband of murdering Lynda Gough, 19, a seamstress, who was last seen in April 1973 when living in Gloucester.
Mrs West, who is also facing two charges of rape and one of assault, will have the new charges put to her at Gloucester magistrates' court today.
Mrs West, the mother of eight children, has been in police custody since her brief court appearance on Monday.
The new charges relate to the discovery of the two young women's bodies in the basement of the Wests' former home at 25 Cromwell Street, Gloucester, by police teams.
Mrs West is accused, jointly with her husband, of murdering Miss Cooper between 9 November 1973 and 27 February this year, and murdering Miss Partington, a student, between 26 December 1973 and 27 February this year. On Monday she was accused, jointly with her husband, of murdering Miss Gough, 19, between 1 April 1973 and 27 February this year. Her remains were unearthed after the diggers excavated six feet below a ground-floor bathroom.
Mrs West was further accused on two separate joint counts of having had sexual intercourse with a girl under the age of 16 without her consent. The girl cannot be named for legal reasons.
Mrs West's co-accused was named as William Smith in one charge and George Purcell in another. She is also accused of assaulting a boy aged about seven.
Mr West is already accused of nine murders involving the discovery of nine sets of remains of girls and women at the Cromwell Street property.
He has also been charged with the murder of his first wife, Catherine, whose body was unearthed in a field 15 miles from Gloucester. He is due to appear again before Gloucester magistrates on 5 May.