Using read-only settings vs. settings repository for Team and User-specific settings in PhpStorm

My team has a git repository that we use to share settings using the Settings repository... feature. We also would like to continue using Auto Sync to to keep changes. However, once our team members begin tweaking user-specific settings to preference, we will need a solution to have the user-specific settings overwrite the repository's shared settings. I am not concerned with project-specific settings that could be specified in a .idea folder, but settings that affect PhpStorm as a whole.

I understand that you can add read-only sources under Preferences > Tools > Settings Repository

My question is, which settings take precedence? If I add a read-only source, does the git repo get overwritten, or are read-only sources overwritten by the synced repository?