Marching Cornicen has the following text: "When you perform a [march] you may treat it as modified by [turn]."
My ultimate question is whether this can be modified by a charge. I'm assuming it can. So the next question is, does the charge modifier you choose have to match straight or turn depending on which you choose to execute with Marching Cornicen? If you choose a straight charge and change to a turn template, do you still get the benefit of the charge?
For example, I dial in a 2-march and select the straight charge as my modifier. I go into the activation phase and reveal my dial. Can I still charge with a turn template? My charge modifier is a straight charge, but Marching Cornicen makes my march a turn instead of a straight. Now, as far as timing goes, both Marching Cornicen and the charge modifier happen when a unit performs or is performing a march, so according to RR 83.9, I can choose which to apply first. I can choose to modify my march with a charge and then modify it with the turn from Marching Cornicen.
So it seems my question is resolved after 10 minutes of flipping through the rulebook, but I figure I might as well post it now in case someone sees a problem with this interpretation that I am missing, or in case someone else has the same question.