Braille Formats does not address this situation directly. Instead, look at sample 2-21 (page 2-50). In the sample Prentice Hall is used as the publisher's name in the corresponding braille. But it is part of a larger company, Simon & Schuster/Viacom.
However, the key to your situation is the print title page. In Sample 2-21, Prentice Hall is not only part of the title, but it is shown to be the publisher at the bottom of the print title page. Simon & Schuster does not appear.
So, with your book, look at the print title page (not the copyright page). What is the text at the bottom of that page? It is ordinarily the publisher's name and/or logo.