The letter (4 Jul 1936 - 2.pdf) is in reality dated 7 July 1936. The day may look like a 4, but is more similar to the 7 of the month (compare with the 4 in the other letter). It is in Dutch, except for the last paragraph which is in German. It is addressed to "my dear husband" (in Dutch) and is signed by "your wife" (in German). In the Dutch part there is a "Liesje" mentioned, who becomes "Lieschen" in the German part.
The second letter (4 Jul 1936.pdf) starts in German and continues in Dutch about halfway down the page. It ends without a signature. But in the middle of the Dutch part, there is the German phrase "Leb wohl, Geliebter".
The undated two pages are in German, but the interesting thing is that at the end, there is a timetable of the return trip of the writer (the mother) by train from Chur to Amsterdam.
Here is my interpretation of the situation: It appears that the mother was staying in St. Moritz in a hotel and visted Lischen/Liesje, presumably her daughter, whereas the father stayed in Amsterdam where he worked at the stock exchange. The daughterl had been very sick before and now stays in St.Moritz at a sanatorium. The family seems to be normally living in Amsterdam and to be bilingual. Lieschen is also bilingual because the writer sometimes speaks Dutch with her.
If you have the originals, it would be wise to scan them again with less contrast because some of the strokes disappear which makes is hard and someltimes impossisble to read.
Andreas Schwab, Montreal, Canada