After the smoke break, return to the wake to find that the LSD has taken effect. Head to the grand stairs and follow Olivia back to her room. Head inside and place the drink on the counter. There’s a gun under the counter so hide in there and kill Olivia’s bodyguards. Olivia will also take part of the shooting so use blind fire when needed and keep track of their movements to avoid getting flanked. Shoot Olivia to disable her then take out the remaining guards if there’s any. Once done, interact with Olivia to subdue her. She'll also tell you where to find DeGarmo.