Conversation so far:
WasPrince Bernhard of Lippe-Biesterfeld married?
Prince Bernhard of Lippe-Biesterfeld married Wilhelmina Helena Pauline Maria.
Who was Prince Bernhard of Lippe-Biesterfeld married to?
Prince Bernhard of Lippe-Biesterfeld was married to Princess Juliana
Did Prince Bernhard of Lippe-Biesterfeld and Princess Juliana any children?
Prince Bernhard of Lippe-Biesterfeld and Princess Juliana had four children
Did either Prince Bernhard of Lippe-Biesterfeld or Princess Juliana have children outside of the marriage?
Prince Bernhard of Lippe-Biesterfeld had two natural, or illegitimate daughters
Were Prince Bernhard of Lippe-Biesterfeld two natural or illegitimate daughters conceived before his marriage to Princess Juliana?
Who was Prince Bernhard of Lippe-Biesterfeld second illegitimate daughter?
Alexia Grinda is Prince Bernhard of Lippe-Biesterfeld's second illegitimate daughter.

Question: Who was her mother?
Self-contained rewrite: Who was Alexia Grinda's mother?