The entire brief table of contents (TOC) takes the place of the full TOC in the first volume BF 2.10.1a and the first
volume also includes, on a new braille page, the portion of the full TOC that pertains to that volume. BF 2.10.1c.
I understand you are asking about formatting the brief TOC. The formatting decisions for the brief TOC are the same for an entire TOC. BF 2.10.1e For example, if the brief TOC was not present and the transcriber was producing a TOC, to show a volume indicator that ends in the middle of a unit, the TOC in the subsequent volume repeats the centered unit or part heading and any listed item(s) in which the volume division occurs. Insert “(cont.)” after the last listed item only. BF 2.10.10a These same guidelines would apply to the brief TOC.
In conclusion, I understand the guidelines to say at the end of volume 1, add a blank line, Volume 2 indicator, repeat the heading followed by “(cont.)” and then add the page number the where volume continues. Because it is a brief TOC, I would not repeat the unit heading.