Originally Posted by Mimi1984
Paul married his nice Friederike, daughter of his Cousin Victoria Louise.
First Cousins once removed - is a mistake.
As Sphero explained above, a niece is the daughter of ones sibling, and Paul had only one niece, Alexandra, queen of Yugoslavia.
As you said yourself, Paul and Victoria Louise were cousins, not siblings, and that makes Frederica his cousin once removed, the child of a cousin.
You are correct that Isabella of Parma gave birth to two living children, but she had been pregnant four times, there was no mentioning how late her miscarriages were.