When you automate your mix functions (volume, pan, mute, and so on), any channel strip group member can act as the mix automation master for that group. When you use that group member to write an automation parameter value, it’s also written for the other group members, depending on their automation mode.
The data is written individually for each channel strip. As a result, you can disable the group later without affecting the automation of any group member, and you can edit or change channel strips individually when they are removed from the group.
For full details about automation, see Automation overview.