My guesses are that D-cup is Eda from the past before she join the Rip-Off Church. And I-cup is Yolanda (the old nun) from the past in one of the omake.
now the question is are they using Japanese or American cup sizes? iirc a JP E would be about a US D. Though given the ridiculous sizes probably US lol
GretelSawyer the CleanerJanet "Greenback Jane" BhaiSister EdaTatiana Yakovleva
From the Light NovelRebecca "Two-Hands", "Revy"Roberta "Bloodhound of Florencia"BalalaikaFabiola IglesiasSister YolandaMakiWashimine YukioShenhuaCaroline/Catherine Morgan
From the Light NovelFloraRevy (Younger)