See lots of detail on the release post about it: Significant feature release: Sync multiple Pixelblazes
The short version is:
- Pick one of the PB as a leader, the rest as followers.
- Decide if you are going to make these a stand-alone network or connected to an existing WiFi network. If stand-alone, set the leader up in AP mode, and connect the followers to it’s WiFi network.
- On the leader, in the Settings tab, add followers.