The first optional conversation appears once you reach the mural of the Queen and her handmaidens.
Go up the steps as Nadine mentions something about female statues, and the prompt for conversation #11 will appear.
In the throne room with the giant Shiva, you’ll have to pull the wheel cranks to move the arms and traverse the statue.
On the left side of the room, after you pull the first crank and move one of Shiva’s lower arms, Nadine will stand at the edge and mention something about the cobra around Shiva’s neck.
Go over to her to activate optional conversation #12.
The last conversation will occur once you have completed the Shiva statue and swung your way over to the next puzzle.
As soon as you turn the first statue to create the prism of light, drop off the platform and stay close to Nadine for conversation #13.