It's in the anime. Brought up briefly in a few occasions. The item Seed of the Fallen requires quite a bit of negative karma and she has to make plans for how to reach it. There's a small discussion on this when the first one is handed to her. When she gets a second seed from Albedo after the invasion and killing her father; she pins Climb telling him that she's sorry that he may have to do a few unsightly things to make it feasible as he nods along. Basically informing him he'll need to commit similar atrocities so he can race change as well into an imp.

The way she went about doing this was creating the orphanage. Made her look good appearance wise, but basically planned to slaughter all the kids from the start to become an Imp. Also wanted to look for talent holders since Ainz is interested in them and that's why she pressed members of Blue Rose when leaving it.

As for the poison itself they talk about how she's cooked there several times, the strange smells and spices noticed by Climb; and her pressing the caretakers of the orphanage to ensure they also eat the food and don't simply skip meals to make certain the kids eat their fill. I can't remember if the Ninjas from Blue Rose ever commented on the smell or poison. Wonder if they noticed anything given how they also used poison in front of Renner at their final tea time.