Regarding Princess Sophie:
Fantastic! Finally an ebenbürtig match! Her grandmother is a Countess Tolstoy born at Tsarskoye Selo in 1917!
With that ancestry it's perhaps not surprising that her brother now has given her a niece named
Alix Imagina Blanca Irmingard Maria Prinzessin von Isenburg.
Imagina might be a reference to several medieval members of the House of Isenburg, the most famous being Imagina of Isenburg-Limburg, 13th-century Queen of the Romans. Blanca and Maria probably in reference to the father's great grandmother Countess Maria Blanca of Maldeghem. Irmingard probably in reference to the 9th-century Blessed Irmgard / Irmingard / Ermengarde of Buchau / Chiemsee, daughter of King Ludwig the German and Abbess of Frauenwörth / Frauenchiemsee Abbey in Lake Chiemsee, where the couple married.