The Shulchan Aruch (432:2) writes that the ba'al habayis can recite the bracha on bedikas chameitz with the whole family listening and then everyone can go off and check a different part of the house. This din is true with respect to other mitzvos as well, e.g. the ba'al habayis can say kiddush or hamotzi for his family and be motzi them in the bracha; why mention it here specifically in the context of bedikas chameitz?
The Maggid of Koznitz (Avodas Yisrael) explains derech derush that the halacha is teaching that when it comes to ridding ourselves of spiritual chameitz, the harmful aveiros and character traits the prevent our spiritual growth, a person has the power to not only influence his own behavior, but has the power to inspire his entire family to do a bedika and rid themselves of chameitz. The Koznitzer Maggid continues that there are great tzadikim who can even influence an entire city to remove their chameitz; there are still greater tzadikim who can influence the whole world to eliminate their chameitz.
“VaYikra Moshe l’kol ziknei Yisrael,” Moshe called together the leaders of Klal Yisrael and instructed them in the laws of korban pesach.” Rav Amiel in his Dersahos El Ami (vol 3 p. 250) asks why Moshe gathered only the leaders to teach the halachos of korban pesach when the chiyuv to bring the korban was incumbent upon the entire nation? Perhaps the answer is that Moshe wanted to convey to the zekeinim that is within their power and it is their obligation, not his alone, to lead, to transmit Torah, to influence the people. (Rav Amiel gives a different answer).
A slave takes orders, he doesn't give orders. A slave is beholden to the influence and whims of his master; he has no ability to impact the course of his own life, much less the life of others. It is this power to be a mashpi'a and not just a mekabeil that marks the difference between a ben chorin and an eved. This idea lies at the heart of the difference between the mitzvah of zechiras yetziyas mitzrayim and sippur. While the former can be fulfilled by internal thought, the latter involves articulating an idea to others. "V'she'aino yodeya loshol -- at pesach lo!"
Have a Chag Kasher v'Sameiach!