I understood. But YOU are basically the tactical coach here. It's YOU who teach the team about what you want them to do, not the other coaches.
To my understanding, the preferred formation is just a note, about what formation the coach will likely choose IF he/she is in your shoes. It's merely about preference. Having one preferred formation, doesn't mean that the coaches don't / can't teach another. I, for example, might have two preferred formations a season (based on who play; the 1st XI or the 2nd), and another different formations the next season. Which one do I prefer, doesn't say much anymore.
Moreover, don't forget that having SIMILAR preferred formation doesn't mean that you both will teach the SAME things, since there are much more things to implement for a tactic to work, outside of formation diagram. YOUR formation is the key here, not your coaches' preferences.