Hi. I tried shift-selecting the hand and the lattice and then duplicating them by using Edit > Duplicate with -1 on the x axis. The hand was duplicated and the duplicate appeared where I wanted it, but the duplicate of the lattice appeared right on top of the original lattice.

Then I started over and I tried grouping the hand and the lattice, and duplicating the group. The hand and the lattice were mirrored properly, but the duplicated lattice was not attached to the points on the duplicated hand that the original lattice was attached to on the original hand. Any ideas?