Theory: The Three Sisters Owned Haunted Towers

Abstract
The Three Sisters are the former owners of the Haunted Towers from Luigi’s Mansion: Dark Moon.

Arguments

 * Argument 1: The Sisters make their first appearance in the game rising out of three tombstones in the Old Graveyard, presumably where people who lived in the Towers were laid to rest.


 * Argument 2: In the Family Room of the Haunted Towers, three portraits can be seen with people resembling the Three Sisters portrayed. Along with that, the picture frames match the mirrors of the Sisters almost exactly.


 * Argument 3: Sister Belinda’s bio mentions that she is an expert gardener, while Sister Herlinda believes herself to be prettier than a flower. The Haunted Towers are a greenhouse-like Mansion, overflowing with plants and an Oak Tree in the centre. It would make sense for the owners of such a nature-filled mansion to be great gardeners.