Question: Who is Margaret Douglas's father-in-law?
Sentence (from "Barthold A. Butenschøn Sr."): Together with Mabel Anette Plahte( 1877 – 1973, a daughter of Frithjof M. Plahte) he had the son Hans Barthold Andresen Butenschøn Jr. and was through him the father- in- law of Ragnhild Butenschøn and grandfather of Peter Butenschøn.
Relevant evidence: No