Illiterate Womens Sircle
Irate Women Simmering
Idle Whinging Sisters
Isolation Ward Sisters
More seriously, how about one of:
Industrious/Illustrious/Incredible/Impressive/Immalicious World Sisterhood
I particularly like Immalicious (having no evil intent), as this would give additional reason why the rest of the sisterhood would be concern about Lainey's predilection for killing men.