Helen - thank you for your efforts! The nun is Sister Lucy Marie Young, 1891-1982 daughter of Lucia Castor and William Young. Sister was born Elizabeth M. Young. I just saw the same photo of the three women two weeks ago - owned by a Mr. David Despres of Grand Rapids. He is a descendant of Lucia.
He allowed me to scan several photos of the Peter Castor and Theodore Castor family, but they are too large to post here. Let me think of a different way to share those with you - maybe in Picassa. Do you use Picassa?
Any idea on when Peter Castor left for Texas or why?