Question: Who is Duchess Eilika Of Oldenburg's father-in-law?
Sentence (from "John VII, Count of Oldenburg"): Count John VII of Oldenburg and Delmenhorst( nicknamed" the Dike Builder"; 9 September 1540 in Oldenburg – 12 November 1603 in Oldenburg) was a member of the House of Oldenburg and was the ruling Count of County of Oldenburg from 1573 until his death.
Relevant evidence: No