On a twice nested object, how to get the local position in terms of the middle parent space

Hi, So, imagine a cube. This is the larger parent. This cube is made up of a bunch of smaller cubes in a 3x3x3 formation. Each of these smaller cubes is a smaller parent made up of six faces. Large Cube > smaller cubes > faces. I need the positions of the faces. transform.position gives me their world position, transform.localPosition gives me their position local to the smaller cubes. I want to get their local position in terms of the larger cube space. If I have to I can take the local positions of the faces in terms of the smaller cubes and convert them with some math, but is there a simpler way? Thanks!