The Chapter Tactic you use is not an option or upgrade nor any part of your Army list. Say when you deploy it.
It's pointless in relation to Pedro and Lysander as you would Always choose Pedro's rulesisn't this sort of pointless as he said Pedro and Lysander...the 2 which have the same ability to make everyone stubbon.
For any other i would say the following.
For Freindly games - Ya fine chose the one you want
For Doubles(Torny or friendly) - Only YOUR army gets it
For Tornys - Clear it with the orginiser but otherwise chose before the game