Q. One who forgot to request dew and rain in his tefilla, and he already passed the bracha of Retzei, and then went back to Shema Koleinu and mentioned it there, is he yotzi? Even though the halacha is to revert to Boraych Aleinu. May one mention it in Shema Koleinu if the alternative is to miss zman tefilla?
A. Shevet Halevi (10: 23) rules that after the fact, if one who did not mention "vesen tal umotor," in the proper brocho, and remembered only after reciting shema koleinu or until almost the end of the amida, and instead of returning to birchas hashonim as required (Shulchan Aruch O.H. 117: 5) went back only to shomea tefila, he complies after the fact.
Horav Shlomo Miller's Shlit'a opinion is similar and in our case, bedieved, in need he may return only to shomea tefilah.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller Shlit'a