This is a hypothetical situation:

If a bank files a SAR that involves a board member, how should that get reported to the Board? Do I need to just be vague in my reporting? Do I only need to notify a majority of the board members and still be vague about it to prevent any accidental disclosure by another board member?

While this may be a hypothetical situation for you, its one I have seen before and one that does occasionally happen. I don't have time to explain it all at the moment, so here is an article where I take a deep-dive into some of the BSA requirements of board reporting on a SAR on a director and even discuss a little know caveat that can be used: https://www.compliancecohort.com/blog/board-reporting-on-director