heyas; why don't you position one, then use the figure:symmetry:right leg to left leg (or vice versa)? if you want the shins the same, but not the thighs or feet, you can pose one, then copy and paste it's dial settings to the other. you could also try turning on leg ik and parenting both feet to an invisible prop, and then swinging the prop back and forth. this might not work so great, though. making an erc is just so intensive (and if you slave one shin to the other, what else would you use that figure for?).... it might be faster/easier to just pose both shins ;)