Here’s what I remember of the book I’m looking for.
It was a collection of short chapters.
Took place in Austria (?)
Main characters were a father with two daughters. Agatha (Agathe?) and Hanni (Hanna?).
Seemed like non-fiction.
The older daughter, Agatha, was ill but in the last chapter was able to walk in her confirmation procession.
But there was a sad epilogue saying that Agatha died some time after the story ended, before adulthood.
I think I read it as an adult but that could still have been 50 years ago.
This must be ‘Gottes Garten’ by Ernst Lothar. It was translated and published in English as ‘The Door Opens’ in 1945. The writer tells the story of his two daughters, Agathe and Johanna (Hanni) who died young. Illustrated by Garth Williams
The English title is The Door Opens, by Ernst Lothar.
That’s the right book. Lothar wrote other novels about his daughter Agathe, who died of polio in 1933. (Hanni killed herself in 1945.) Agathe was a friend of Manon Gropius, the daughter of Alma Mahler-Werfel and Walter Gropius. Manon, too, died of polio.