Questions about how to predefine a new texture mapping?

Hello, thanks for your open-sourced work! I wonder could you give me some suggestions on how to generate the "uvfaces_v2.pth,  faces_v2.pth, vertex_uvcoords.pth"?  As the original num of faces of FLAME is 9976, how did you transform it into a new form of 10006 faces?

Thanks a lot!