You can do the poison opportunity on Francesca without actually wasting your poison at all
Sadly, while it counts as poison for Silent Assassin purposes(body won’t be found), it counts as “Any Method” for contracts mode, which prevented me from doing an amazing puzzle around it
credit to @Notex for the discovery
Before you ask, this is a Francesca exclusive thing, doesn’t work on anyone else. You can get other people to pick up items that are placed in the same spot as a drink, but it won’t poison them.
A syringe also works.