Blessing of the children is the blessing for the father.
Rashi explains why Vayechi is a parsha s'tumah, a 'closed' parsha, lacking the usual space before the beginning of the parsha. Klal Yisrael's eyes and hearts were 'closed' and clogged because Yaakov Avinu was niftar. Another reason is because Yaakov wanted to reveal when the Final Redemption would be and his vision became clouded/closed.
Why was Yaakov's wish to reveal the Final Redemption not fulfilled?
The Zohar asks a question on the bracha that Yaakov gave to Yosef, 'Hamalach hagoel osi yevarech as hane'arim veyikaray bahem shmee' etc. We do not find Yaakov blessing Yosef at all, only his children were blessed (hane'arim). The Zohar answers: the bracha of the children is the bracha of the parents, 'birchasa dibnoi hen birchasa de'aba.' When Yosef's children were blessed, it was Yosef who was blessed thereby.
The Gemara relates that HKB"H asked R' Yishmael Kohen Gadol for a bracha, Yishmael bni barcheini. R' Yishmael answered, 'yehi ratzon shiyichbeshu rachmecha es kaascha veyagoilu rachmecha al midosecha,' - that you act with mercy and kindness towards your children - Klal Yisrael. Same question here, where is there a bracha for HKB'H in this?
The answer is the same as above. When Klal Yisrael receives blessing and kindness then HKB'H (keveyachol) is blessed as well, because "birchasa debnoi hen birchasa de'aba." The opposite is true as well, when Yaakov Avinu was niftar, and the eyes and hearts of Klal Yisrael were closed up and clogged, the Torah was affected as well and became closed/clogged, so to speak. That is our hope, if our tzaros and suffering affect Hashem (kevayachol), then He will surely help us.
Bikesh Yaakov legalos es ha'ketz' venistam mimeno. In this, the Redemption is alluded to. Because the pegam, the 'blockage' was able to influence Yaakov himself, venistam mimeno, and the Torah was affected as well. When the tzaros of Klal Yisrael are so overwhelming and reach such proportions that the yeshivos and shuls cannot function and all yidden are afflicted, then we can be sure that Hashem will help us.
Aish Kodesh, by Rebbe Klonimus Kalman Shapira zt'l zy'a, from Piasezcna, a collection of the Torah he said in the Warsaw Ghetto during WWII