And Karen is definitely retconned.
There's a Karin in New House - one mention as the cook. The next mention is of a Karen in Carola, years later, as an old friend who had come from the Tyrol.
In Mystery, Tom, Rosalie, Peggy, Carola and Bride there is only a mention of "Cook" with no name. In Rosalie she's explicitly Megan (Gwensi's nurse)'s sister. In Carola along with Carola, it's said that Cook is from near Bosherton.
Ring the bells that still can ring; Forget your perfect offering
There is a crack in everything; That's how the light gets in
Anthem: Leonard Cohen