RAV SHEYSHES WAS ANGRY THAT RAV IDI DIDN'T SAY BSHEM AMRO.IS THERE ANY MORE OF A ZHUS WHEN YOU DONATE LSHEM A NIFTAR PUBLICLY VS PRIVATELY (OR ANONYMOUSLY)& HAVE THE NIFTAR IN MIND HASH-M KNOWS WHERE TO APPLY THE CREDITS?
The Halachah of b'Shem Omro mentioned in the Gemara relates to Divrei Torah alone. It is a special Zechus that when one's Divrei Torah are quoted after one dies, it as if the Niftar himself had said it; "Sifsosav Dovevos ba'Kever." I once heard that this is unique, for a person can no longer earn his own Zechusim once his Neshamah is no longer attached with the Guf; in this case, the Guf itself talks. However, this does not relate to other Zechusim which are credited to the Niftar's account, and seemingly would not apply to Tzedakah which, as you say, we can leave the accounting up to Hash-m. The only rationale I have seen for publicizing is from the din of Mefarsimim Osei Mitzvah, which applies if others will learn from it. In addition, if someone donates something which can be used for a Mitzvah, such as a Sefer or a Shul, there is a possibility that the future user will also take the opportunity to credit the Niftar.
D. Zupnik
See the modern sefer mishnas yaakov on agadata, introduction to chelek beis, for a beautiful interpretation on the subject.
YCDC
Although here, Rav Sheshes had not yet died, so is it just a related principle that the zechus transfers, or will his lips move at a later time after he dies as a result of being quoted during his lifetime? (unless we say Rav Sheshes was blind at this time, hence considered as dead; this is difficult since he was alive as far as being able to say Divrei Torah)
Kol Tuv
Mark Bergman
Although your first suggestion is certainly possible, I personally understood that Rav Sheshes was concerned that the Divrei Torah should be given over in his name so that in the future the Shemu'ah would have his name on it and be said in his name after he was Niftar.
D. Zupnik