Thank you for writing to us with your very thoughtful questions. While we are not experts in this particular field, to our best knowledge there is no official source that has been universally adopted on these points. The fact that you report working on your own in-house manual would itself seem to confirm this; accordingly, developing your own manual seems like a good idea.
Our own view is that several different policies regarding consensus decision making are justifiable, and one criterion for the “best” may be a policy that your group will agree to and use in practice. In different words, whatever policies or guidelines you do adopt need to be both agreed to and followed by the members of your organization, over and above their particular content. The same basic analysis would probably apply to vote-switching as well.
One source that has impressed us and shaped our own thinking is Facilitator’s Guide to Participatory Decision-Making (3rd edition), by Sam Kaner et al. The authors there point to different meanings of “abstain,” and different degrees of “consensus,” which they regard as different from “unanimity.” We found their chapter on “Striving for Unanimity,” toward the end of the book, to be especially thought-provoking and enlightening.
In addition, in your own work, once you have arrived at decision making policies, you might also decide to review them on an annual basis, to see if they are working as intended, and if any adjustments might need to be made.
Regarding training, we don’t usually do formal training\on consensus building, but you could write my colleagues at toolbox@ku.edu, mention that you wrote to Ask an Advisor, and see if they have any leads. Alternatively, you might try to track down the authors of the Kaner book.
We hope this much may be helpful to you. Thanks again for writing, and all best wishes as your important work continues.
