Design var. Pattern Grouping - 3-plane sym

Hello,

this question is about the 3 plane symmetry option in the pattern grouping tool.

I am planning to use it for a composite optimization.

If I understand the function right, it should be possible to create three planes that function as symmetry planes for the layup.

The anchor point sets the position of the plane and defines, together with the grid points, the normal vector of the respective plane.

This works good with the 1 plane sym (one anchor point and one grid point) and the 2 plane sym (one anchor point and two grid points). 

But if I select the option of a 3 plane sym, I can still only select one anchor point and two grid points. 

So how can I define the normal vector of the third plane?

Or is it somehow defined by the other two planes?

Thank you in advance!