This very important article on contact merge permissions is missing from the main NPSP doc page: https://help.salesforce.com/s/articleView?id=000355549&type=1
Furthermore, it says "all classes mentioned in the Winter '21 Release Notes" but the release notes link is broken, so it's not even complete.
Salesforce needs to collect this important information and incorporate it into the main doc page.
Thanks for your feedback, @Matthew Martin. Apologies for my delayed response; I was on PTO and doing my best to disconnect from work.
No doubt about it, permissions for NPSP features (and Salesforce in general) are a bear. The docs team is doing our best to cover that information in NPSP help docs in lieu of managed permission sets in the package.
I'll create an internal ticket for our team to consider an update to NPSP docs. Please be patient as our Salesforce for Nonprofits documentation team is a bit smaller these days. Thanks again!
