Non-Lethal playthrough - no detections, no enemies ever alerted, several knocked out. Party Invitation from Artist's Safe in inventory. Entered Boyle Estate Grounds (neutral) through Blinking into the garden where Shaw is waiting. Shaw duelled, knocked out with Sleeping Dart. Disabled huge Wall of Light blocking stairs, accessed Wale Oil room through rat tunnel from upstairs. Robbed Basemant Vault. Knocked out all guards on 2nd floor, stashed all in attic/mezzanine connecting Esma and Waverly rooms. Searched all rooms, know which Lady is target. Non-Lethal option not acquired yet.

After taking care of all the guards on the 2nd floor and looking through all the rooms, I exited from Esma`s room to the Gardening Balcony. I played around outside on the Estate Grounds with some of the guards and explored - no detections, one possession - going "backwards" to finally arrive at the front door - from the inside. It started when I went back inside, entering Boyle Mansion Foyer, the Overseer, the one in the second video became hostile and started attacking me on sight.
I thought I maybe had gotten detected or they found a body, so I reloaded the Autosave from just after I left the Mansion from Esma's room to the Gardening Balcony. I immediately re-entered the mansion, went downstairs to arrive near the ground floor exit towards the Garden, the stairwell an overseer stands right next to (the starting area in the videos). The first few times all the maids detected me right away and became hostile. Then happened what you can see in the vids, either only one or two maids became hostile (video 1) or none of the maids became hostile, but the Overseer in the Foyer became hostile.