Thank you for your question.
This is really a Formats Manual question, but I think I can steer you in the right direction.
The only reference I can find to multiple print books in a single braille volume is in the 2011 Braille Formats manual.
Sect. 2.2.1c Several titles of a series may be bound together by the publisher, with individual title pages, ISBNs, etc. A title page, and a second title page if necessary, is inserted before the beginning of each title. Each new title page begins with braille page t1.
I can't find anything that refers to dedication pages specifically, but since the above reference directs us to insert the title page before the beginning of each new title, it would make sense to do the same with the dedication pages.