Q. If many people are present when Havdala is said and it would take a long time, probably more than the time it takes to recite the complete Havdala, for everyone to smell the besamim, what should be done so it will not be a hefsek?
A. Shemiras Shabbos Kehilchoso (60: 7), writes that if many are being yotze with the Havdala, it may not correct to wait until all take a turn and smell the few available besamim, since it would create a great interruption between the brocho on the wine and the rest of Havdala. On note 21 quoting HS’Z Auerbach Zt’l, that he maintains it may not be a hefsek even if the wait is longer than the recitation of the Havdala, and they may also smell after that, without making an additional brocho.
Salmas Chaim (200) maintains that if they listened to the brocho, they do not have to repeat it after the end of Havdala.
Sefer Chofetz Chaim Upoalo (3: p. 511) relates that when there was a large crowd listening to Havdala, the Chofetz Chaim would not recite during Havdala the besamim brocho. He left it for the present to recite the brocho when the besamim came to each of them. (See Piskei Teshuvos 297: 2)
Horav Shlomo Miller’s Shlit’a opinion is that the listeners should smell the spices after the end of Havdala and after reciting then their own brocho.
Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit’a