How do I find the new will?

First, wait until the will reading.

You'll see George around.  If you've been investigating properly, you'll know
that he was left out of the new will, but he *was* in the old one.

Maybe he has the solution.

First, you'll need to make him crack, so he'll get the will.

Show him the calendar from the library to him to make him nervous.

Follow him upstairs, but don't go into his room.

Instead, go into the library.

Hide outside, and wait for George to come.

He'll open a secret passage!  Once he goes in the passage, enter back into
the room.

Save the game at this point, this requires a bit of experimentation.

Look at the bookcase, and you'll find a button.

If you press it right away, George won't open the safe inside, because he
doesn't have time.

Instead, wait about 4 turns.

Then, press the button, and head on in.