Is it permissible for the suitor to see the fiancée with his mother or sister, without a mahram for her, and is the determining factor the khalwah (private seclusion) or the absence of a mahram?

A man who wishes to marry a woman is permitted to look at her, with or without her knowledge, based on the saying of the Prophet, peace and blessings be upon him. This looking must be for the purpose of marriage, not for pleasure or lust. The presence of a mahram or her permission is not a condition, but being alone with her is forbidden. Social customs should also be observed.