Hirohiro-sama
This is Kawaguchi Hidetoshi. This is my humble answer to the question.
After that, I wonder how the younger brother, his wife, and everyone in the family are doing... I'm guessing that there is still more sadness and loneliness... in particular, it seems that the wife's mental and physical burdens are considerable, so I know that support, help, and encouragement not only from the husband, but also from everyone in the family around them will be important.
Also, if I had the chance, I have introduced you several times in Hasunoha's answer, but I believe that if you watch the movie “Born” (http://www.umareru.jp/) by all means, the younger brother and his wife, and of course Hirohiro and his wife, it may be a source of awareness and healing for many things, even just a little bit.
Movie theater screenings have already finished, and no DVDs have been distributed, so I'm sure they will participate in independent screenings nationwide, but I watched Chusei during the national screening, and I really noticed a lot of things, and I'm still thankful for that.
When confronted with a reality where things we take for granted are not taken for granted, we often get lost and suffer... Of course, in Buddhism, it is hoped that we can clearly understand the real world state of this suffering, where it is impossible to take it for granted, and then think about how we should go beyond that worry and suffering.
To that end, when faced with difficulties, it is necessary to face those difficulties head-on and aim for solutions little by little.
Of course, it may take some time to face the painful reality of stillbirth head-on, but I pray that with support, help, and encouragement from everyone around you along with the definite memorial service of Mizuko, you will be able to face each other little by little, and eventually overcome suffering and sorrow through various healings and realizations.
Kawaguchi Hidetoshi Gassho