You continue to rock at detecting. Re: little Sophie Henriette, by far the most plausible assumption is that she went to the relations as well. Because then Hans Heinrich can dismiss any of his staff who doesn't directly serve him until he remarries, thus saving considerable household expenses. As Prussian noble families are more or less permanently in debt, that's an issue. And seriously, as a military man, he's not at Wust most of the time anyway.
Also: ties between Prussia and the Netherlands were strong ever since the Great Prince Elector, lots of intermarriage from the royal family downwards, Dutch merchants in Prussia, Prussians in the Netherlands etc., Protestants unite, etc., so studying in Utrecht by itself isn't that unusual for a Prussian nobleman. But in context, it furthers the idea of him having spend a part of his childhood in the Netherlands. Mind you: Katte going to the university at all instead of directly to the army also says something about his likes and dislikes.
(None of the Hohenzollern princes of that and for a few more generations got to have a university education, though the later Hannovers did, being primary patrons of the university of Göttingen, which a great many of the British male royals went to in the 19th century. Oh, and Wilhelmine's husband the Margrave, Other Friedrich, went to the university of Geneva, not least because his father was a Calvin Forever! guy but also because Your Mother is an Adulturous Whore I Locked Up, Be Educated Elsewhere!)
Re: Kattes and Bismarcks
Also: ties between Prussia and the Netherlands were strong ever since the Great Prince Elector, lots of intermarriage from the royal family downwards, Dutch merchants in Prussia, Prussians in the Netherlands etc., Protestants unite, etc., so studying in Utrecht by itself isn't that unusual for a Prussian nobleman. But in context, it furthers the idea of him having spend a part of his childhood in the Netherlands. Mind you: Katte going to the university at all instead of directly to the army also says something about his likes and dislikes.
(None of the Hohenzollern princes of that and for a few more generations got to have a university education, though the later Hannovers did, being primary patrons of the university of Göttingen, which a great many of the British male royals went to in the 19th century. Oh, and Wilhelmine's husband the Margrave, Other Friedrich, went to the university of Geneva, not least because his father was a Calvin Forever! guy but also because Your Mother is an Adulturous Whore I Locked Up, Be Educated Elsewhere!)