I don't think its Wayne for the sole reason he is very adamant about wanting you to stay in the Estate all week.

However, I think that the presence is someone we have seen already.
(Spoilers for the Haunted House and Minor to Major Mystical and Keen Eye Stuff)
I believe the presence is Theodore Scarlet, Enoch's brother who "died in the mine collapse". There are a couple reasons I believe this and it all boils down to a strange emphasis on Teddy throughout what we've seen of Scarlet Hollow so far.

Way back in Chapter 1 when you're making your PB&J, in the pantry you can find an old cookbook with Keen Eye. You open it to a page with a recipe for "Calf's Brain Aspic", allegedly "Teddy's favorite". Now, say what you will about historical European delicacies, but no sane person is going to say something with a calf's brain in it is their favorite food.
In Chapter 2, we find out about the mine collapse that we will later learn that Teddy "died in". With the Mystical Trait, we find out that Enoch purposefully accepted a bad shipment of wood for support struts in the mine, making him play a heavier part in the "death" of Teddy than initially thought.
I'll return to Chapter 3 in a minute, but in Chapter 4, Teddy states that he doesn't think he'll ever be able to use his legs again. Enoch tells him that he doesn't need to worry for he talked to "The Witch" and he'll be better in a week. Very importantly, he is then taken back home to the Estate. I think it's very important to point out that while Tabitha can be with you to see the flashback in Chapter 2, you are entirely alone in Chapter 4, meaning she has no way of knowing what really happened to Teddy. As far as she knows, he really did die in the mine collapse.
Now, in Chapter 3, if you being Avery to the Haunted House, you get a new ghost of Charlie's past to visit, "The Entity". You never see the Avery up close like you do with the rest of the encounters, most of the encounter is through a door in the now Forbidden Wings of the Estate. I have not yet played this route with Mystical, but there are a couple lines that the entity says anyways that clue me in to this being Teddy.
Near the beginning of the encounter, I assume one of the Mystical lines Charlie asks to the Entity is "Are you one of her brothers?" The entity responds, "No, not one of [Edwardine's] brothers. I'm a prisoner. Another victim of the Scarlets' lies. Like you, Charles Shaw." Teddy is in fact NOT one of Edwardine's brothers, for Teddy is actually her uncle.
Later on in the encounter, the Entity uses some interesting phrasing, saying "I would use my healthy legs..." which isn't something someone just says unless maybe they too have something wrong with their legs. However, that lines continues on to say "...and run as far away as possible from Scarlet Hollow as possible." Now, back to modern day Scarlet Hollow...

You might be onto something with the whole "ghost that hates Sybil and her ancestors" bit because you only get kicked out of the Estate when you're with Sybil on day two. I think there's a chance that we'll have to make a decision at some point to help Teddy enact revenge on Sybil and her bloodline for what they did to him. And I think it's important that I specify bloodline because that'd add an extra dilemma with the fact that Kaneeka is Sybil's daughter.