Can minhag hamakom allow you to make what is for you a bracha levatala

Question

I have a question about a specific case but it relates to a broad subject so I'm making the question less narrow.

Pesachim 101a presents a minhag they used to have to make Kiddush in synagogue. Even though one has to make Kiddush where they are eating (Orach Chaim 273:1), the gemarra says they would have guests eat and sleep in the synagogue. Today even though there aren't guests in the synagogue, in some places the practice continues (although some aren't happy with this practice, see Orach Chaim 269:1). While the Ran in Pesachim 19b says those that continue the practice hold it's a takanah that Chazal instituted, the Mishnah Berurah (OC 269 SK 5) understands that it's a minhag.

Consequently, a person who doesn't have such a minhag, seemingly if they would make Kiddush in shul it would be a bracha levatala (see Tosafos on 100b: והיכא דליכא אורחים סמוך לבהכ"נ אין לקדש דהויא ברכה לבטלה).

Now, there is a discussion about making a bracha on a minhag, I'm asking even if one would normally make a bracha on a minhag, what about where they don't have this minhag? If such a person, let's say is a guest at a synagogue where they do have such a minhag, if they ask him to make Kiddush would he be allowed? There is a concept of following minhag hamakom, but I'm wondering if it would allow making a bracha one otherwise wouldn't be allowed to make.

Edit: it seems my example of kiddush in synagogue isn't the best (either it's not a minhag but a takana, or even if it's a minhag it's not an individual's minhag but a congregation). Perhaps a better example is saying a bracha on hallel on Rosh Chodesh. Sefardim normally don't (OC 422:2) (although I wonder if that's dependant on making a bracha on a minhag...). What if a sefardi is asked to lead hallel at a synagogue that says the bracha? Can they? Should they?

Edit2: @DoubleAA confirmed my suspicion about Sefardim and Hallel being connected to saying a bracha on minhag. Per their advice, new scenario as an example for this question: An Ashkenazi who doesn't say Hallel on Rosh Chodesh being asked to lead Hallel at another synagogue. Can they say the bracha? Should they?

Answer 1

For those who make Kiddush in Shul on Friday night (or Yom Tov night, though that is limited - not on Seder night, not on Sukkos, not on Shemini Atzeres (outside Israel)), there is a very real issue of a Brachah Levatalah. The solution (I have discussed this with my Rabbi and I have seen similar practices elsewhere) is one of the following:

• If there are children present who are old enough to understand the concept of a Brachah before eating (or drinking in this case), the Brachah is made on their behalf. As I understand it, ideally the children (combined) should drink at least the majority of a Reviis - so 2 or 3 drinking little cups is enough, but if there is only one child then he/she should drink more than just one little cup.
• If there are no children present, then the person making Kiddush must drink the entire cup. Simply drinking a Reviis or most of the cup is not sufficient because it must be Bemakom Seudah. By drinking the entire cup (not sure how big that cup needs to be - our Shul has a fairly large cup) it is treated as a Seudah in and of itself, or at least enough to make it Bemakom Seudah.

The same rule applies with a Bris on Shabbos (or Yom Tov). Normally at a Bris, the Rabbi drinks a little sip and that's it. But on Shabbos right after Musaf, the Rabbi must have Kiddush Bemakom Seudah - and can't eat/drink anything (except perhaps water) without first making Kiddush. If the Bris is in the same room as the actual "Kiddush" for the congregation there is no problem. But if the Bris is in the Sanctuary and the "Kiddush" will be in another room, then the solution is for the Rabbi to drink the entire cup (and I have seen my Rabbi do that, and I confirmed that this was why he did that).

Answer 2

Based on my memory in dealing with hilchot brachot; no, you may not make the bracha if it's a bracha l'vatala for you(unless you move there).

The reason is that one cannot violate a Torah or Rabbinic precept, even if others do so. One famous example is a Sephardi who finds himself praying in an Ashkenazi minyan on rosh chodesh where Ashkenazim bless on the hallel(while Sephardim don't). Since it is not his minhag to bless, because it is forbidden by the Torah("lo tisa et shem HaShem lashav"), he is forbidden to make the blessing or even answer amen. Related, the Mishna Berura in Biur Halacha(don't recall exact place) suggests that answering amen to a bracha that one does not make, does not violate an issur(not that one should bless it; although most poskim rule not answering amen on such berachot. See Yalkut Yosef 422:2-5).

However, if one settles into an area that does make the blessing(even though their personal tradition is not to), they may make the blessing if they choose to. A guest in the community, however, must adhere to their stringencies and not make the bracha.