Dear Rabbi. As we spoke I render also religious services at an old age home. I have great concern when the elderly recite Hallel, as they do now during Chanuka and before they begin they say the bracha. Since I understand that even when missing one word of Hallel, if one does not repeat and say it correctly the bracha at the beginning will be rendered in vain (Levatala). Should I not then stop the people of saying that bracha?

Indeed Mishna Berura (488: 2 – 3) debates if when a word of Hallel was missed if the brocho recited is considered in vain. Kovetz Halochos (17: 12) and others rule that it is a brocho in vain. and one should be careful not to miss any words of Hallel. Horav Shlomo Miller Shlit’a suggested that you should say aloud the brocho and announce that they listen and comply with it. The Rov added that you should preferably also recite the whole Hallel aloud for them and they should say it together with you.