Track Groups have a property titled Select which, if enabled, cause Ardour to propagate a region selection in one track of a group to the corresponding regions of the other tracks in that group.

This can be particularly useful when an instrument has been recorded using multiple microphones (e.g. a drum kit): by enabling the Select property for the group, selecting a region in one of the tracks, Ardour will select the corresponding region in every other track of the group, which in turn means that a subsequent edit operation will affect all the tracks together.

How Ardour Decides Which Regions are "Corresponding"

Regions in different tracks are considered to be corresponding for the purposes of sharing selection if they satisfy all the following criteria:

1. each region starts at the same offset within its source file,
2. each region is located at the same position on the timeline, and
3. each region has the same length.

Overlap Correspondence

Sometimes, the rules outlined above are too strict to get Ardour to consider regions as corresponding. Regions may have been trimmed to slightly different lengths, or positioned slightly differently, and this will cause Ardour to not select regions in other grouped tracks.

In this case, changing Edit > Preferences > Editor > Regions in active edit groups are edited together: to whenever they overlap in time will allow regions in different tracks to be considered equivalent for the purposes of selection if they overlap. This is much more flexible and will cover almost all of the cases that the fixed rules above might make cumbersome.