Rav Moshe Shternbuch - Who Leads The Seder, The Father Or The Zeidy?
Seder night is often a large family gathering with three generations present. Often times the grandfather will lead the seder and lead the dialogue with his grandchildren. Rav Moshe Shternbuch (2:236) raises the issue that on this night there is a special mitzva of “ViHegadita L’Bincha”; a father must tell his child the story of Yetzias Mitzrayim. How can he sit there idly and be Mivatel a Mitzvas Aseh while the grandfather does all the telling?
He answers that the father can be Yotzei his Chiyuv by making the grandfather his Shaliach. In fact the grandfather with his age and experience can probably do a better job of instilling emunah, the whole point of the seder, into the young children. Similarly he brings the Hafla’ah in Kedushin (30a) that says there is a special mitzva for a grandfather to give over Torah to his grandson since he is higher up on the chain to Har Sinai than the father.
So while its perfectly okay to let Zaidy lead the seder, nevertheless the father should actively participate and contribute to the conversation. While technically his is Yotzei by making the grandfather a shaliach there is a klal, “Mitzva Bo Yoser MiBishulcho”; it’s not the same unless you do it yourself.