Arcos de la Frontera - Home of Mother Henrietta or Mom Hen
I had fun looking at different places around the globe as I decided where Ed and Mel would be traveling. I decided their friend, Mother Henrietta would live at the convent in Arcos de la Frontera. The village has a castle, and there is a convent. I don't know much about it, but it looks like you can order a sweet treat from the nuns through a small door with a turntable.
Check out the village of Arcos de la Frontera and the information on the convent (see the Convento de Mercedarias Descalzas).
While the nuns at Convento de Mercedarias Descalzas may be cloistered nuns in real life, in "The Black Silk Path" Mother Henrietta is eager to help Ed and Mel find their parents.
Definitions (links to Merriam-Webster):