Here is "Basement 3" for the whole area -- beneath the mansion, the graveyard, and the church. It shows both the municipal sewers as well as secret places carved out of the rock.

Secrets Hidden

The built-out area in the upper left in below the mansion and the rocky outcrop it stands upon. The broken-down part of the sewers, in the upper middle section, are beneath the ruins on the main outdoor map. Whatever destroyed the buildings there also caused damage to the sewers below, damage that has not been fixed. The stairs near the center of the map ascend into the area below Briarheath Tomb, the family tomb in the center of the graveyard. The portions of the sewers that jut out from the main sewer lines are portions that go beneath the houses on the first map.

I still have more furniture and stuff to add, and then I will write up an explanation of everything that is happening in this sophisticated criminal enterprise.

Secrets Revealed

This version shows secret doors and passageways. From the mansion, you can descend through secret passageways and stairs down to a third basement, which has a secret access to the sewers. From the sewers, you can then pass through one of three other secret passageways to another built-out area that includes stairs rising into the area beneath the Briarheath Tomb. You'll recall from earlier in this thread that the area beneath the tomb also includes a secret passageway to the church. That allows those in the know to be able to clandestinely travel between the mansion, the church, and the graveyard, though it requires hiding from sewer maintenance workers when using the sewers to travel between disconnected secret sections.

When the mapping is all done, I am going to write this up like a proper D&D campaign module.

Here is Basement 2. Most of it is taken up by the mansion's sewer system, including a branch that comes from beneath the barn. There are shadows from the shafts above where waste is deposited into the sewers. Waste flows to the southern-most part of the line, where a chute connects the mansion's sewers to the municipal sewers. There are also two shafts here to connect the wells (one in the barn) to the water table below.

The secret stairs from the wine cellar connect to a small area here, with more stairs continuing even further below.

Here's a zoomed-in look at the chute that also shows a closer look at the effluent (with sheet effects copied in from Sinister Sewers).

Here is the first level of the basement. Like the church mapped earlier in this thread, the upper quarter of this level is actually above ground, allowing for windows near the ceiling to allow in daylight.

This floor is primarily used by the servants. It has two stoves for cooking and a furnace used for heating water, a washing area for scrubbing dishes and doing laundry, two bathtubs and two toilets, a staff dining area, a wine cellar, and sleeping accommodations for the servants. Those include three private rooms (two of them barely more than closets) and a shared room with four beds. There are two additional servants' rooms in the attack, and a few more (unmapped) in the barn. Most of the walls on this level (except for the wine cellar) are lined with wooden paneling to make it a little cozier that the stone walls of the outcrop the mansion is built upon.

The servants' spiral staircase goes down one more level to a Basement 2 area mostly used to provide access to maintain the pipes used to carry the runoff to the sewers. A secret room off of the wine cellar leads to stairs that descends to a separate, disconnected part of Basement 2.

Top story of the tower. On to the wine cellar (and the rest of the basement).

Ooops, I posted an older version of floor three. Here's the correct one.