Two workarounds. My approach would be to copy the stack of clips to a new timeline. Place it a few seconds into the timeline so later you can extend both head and tail if you need handles. Replace the shot in your timeline with the timeline containing the clip stack. That way it looks and behaves like a compound but you can change anything in the new timeline and it represents in the original timeline.
An alternate method – go to deliver and render the file so all the keys are baked in. Edit new clip in original timeline in place of the stack.