If a person declares verbally that so and so woman is his sister (in Urdu 'mu boly bhai behn'), can they meet and talk like real brother and sister?

Bismillahir Rahmanir Raheem

Assalaam alaikum wa rahmatullah

Please note that he will still be a non-mahram and talking to a non mahram, meeting with him or going out with this person is not allowed for her. She is required to observe complete Hijab with him. Islam does not encourage a relationship between a male and female who are
non-Mahram to each other.

Why is Hijab necessary?
http://islameasy.org/hijab.php


And Allah knows best.

Ask Alimah Department