Rav Greenblatt, a prominent posek and talmid of Rav Feinstein, saw brought down in the sefer of the Maharil Diskin (Rav Yehoshua Leib Diskin), based on earlier sources, that the daughter of Avraham Avinu died on the same day that Sarah died. This all originates in the Gemara Bava Basra 16B, which we examined in some detail before, which assumes that Avraham had a daughter according to two opinions. Did she actually die on the same day as Sarah Imeinu? Rav Greenblatt inquired about this from his revered rebbe.I think I know exactly what the source is for Sarah's daughter dying the same day Sarah did, because I myself felt compelled to create this self-same neo-medrash.
"I did not see (this information about her dying) in the midrashim which I possess", answered Reb Moshe. But Reb Moshe adds that this is not necessarily a proof; just because it was not seen in these seforim, it is not definitely false. However, Rav Moshe Feinstein adds that it is highly unlikely that such a tragedy occurred in Avraham's family...
If the daughter passed away during Avraham's lifetime, what kind of magnificent bracha could this have been? Also, it seems impossible that this daughter could have died on the day Sarah died. How so? The order of the psukim teaches us this. The death of Sarah is recorded right in the beginning of our parsha, in 23:2. The birth of the daughter to Avraham is in 24:1, AFTER Sarah died! Consequently, this daughter could NOT have died on the same die [sic = day] Sarah died.
In conclusion, states Reb Moshe, "it is clear that it is some type of error...as we see that it is not found in the words of our rabbis, the early commentators (rishonim)". Reb Moshe adds that "until now, I have not seen the sefer of the Maharil Diskin on Chumash, but I will attempt, b'li neder, to see it".