Braille Textbook Formats Section 7 is exactly where you should be. Pay close attention to the guidelines for blank lines after centered headings. Look at the brailled examples in the Formats Manual as well.
The Literary Instruction Manual also outlines this nicely on the bottom of page 19-11. The rules/guidelines would be the same for any volume that does not have volume numbers listed in the Contents pages.
Since this is for your manuscript, I'm sorry I can't give you the exact answers, but I hope I have helped to steer in the right direction.
Good luck with your manuscript!!