You found Alice!
My Uncle believes that Martha was Ivy's Great-Aunt. Unsure whether that was on Ivy's Mother's or Father's side though.
Do we know if Alice was Ivy's mother after all? There's definitely a link as my Grandmother once told him that Ivy had a half-sister called Mima.
If so, is it looking increasingly likely that Ivy was born illegitimately, was raised by Martha for time before being returned to Alice?