Question: All of Isaac's followers in this film are young people, no older than about their mid 20's. So why in the opening scene during the Cafe slaughter, is there a elderly lady helping them do their dirty work (the worker who poisons the coffees). This makes no sense at all considering it's the older people they were killing.
Chosen answer: Who knows? Maybe they blackmailed her, because she works there, and the children wouldn't get caught poisoning the coffee, or maybe she isn't as old as you think, she could well be in her mid 20's, it's hard to tell, you only see her briefly.
She is obviously in her late teens, early 20s.
Answer: For letting the two adults into the town and disrupting the pact they made.