Yes, the primary source of information for the preferred name are resources issued by the bodies, and the name as found on the title page.  You're not required to do further research unless you have a conflict between two entities that have the same preferred name.  The only thing you have to determine is whether "Working Girls Societies", "Working Girls' Clubs", and "Working Women's Clubs" are corporate bodies in and of themselves.  If they are, then you would have subordinate entry instead of the direct entry you show below.  It doesn't seem as if any of them could be considered entities unto themselves, so I think the access points you have given below are correct.

If authority records were being established for these conferences, they could be linked together using see also references for the earlier and later names.

Adam Schiff
University of Washington Libraries

From: Program for Cooperative Cataloging [mailto:[log in to unmask]] On Behalf Of Jessica Janecki
Sent: Tuesday, March 28, 2017 2:08 PM
To: [log in to unmask]
Subject: names of individual conferences/meetings

I have the conference proceedings of 3 conferences/conventions/meetings. As far as I can tell, they are all the same conference series. However, the name of each is different. I am doing monographic cataloging and I want to construct an AAP for each individual conference. Is it as simple as choosing the preferred name directly from the piece?

For example:

National Convention of Working Girls Societies $n (1st : $d 1890 : $c New York, N.Y.)

National Convention of Working Girls' Clubs $n (2nd : $d 1894 : $c New York, N.Y.)

National Convention of Working Women's Clubs $n (3rd : $d 1897 : $c New York, N.Y.)

Jessica Janecki