Using Compound Clips
Compound Clips in Final Cut Pro are user created clips of individual or grouped elements nested together. To create a Compound Clip select one or more elements in the Timeline or Browser, right-click, choose "New Compound Clip..." & title the clip in the window that appears.
Compound Clips are frequently used to have retiming control over template animation speeds, and unifying element dimensions when working with transform effects.
Watch the video below for tips & best practices for using Compound Clips.
Refer to Final Cut Pro User Guide for more details about Compound Clips.