Unfortunately there really isn't much else to be done for this. Editing in Parent Tracks is simply not a reliable or sustainable workflow with the new comping scheme.
What you are editing is not a single clip or comp. It is merely a visual representation of what is currently audible (and even then overlapping clips may not be visible).
What I suggest you do at this point, if you don't want to break open lanes and edit there, is right click on the Parent Track and select Flatten Comp. This will create a single clip that will respond the way you want much better and ignore (usually) everything else in the other lanes (while preserving the original clips).
To edit it though you are going to need to Right Click on the newly created clip in the Parent Track and unlock the clip (or use the unlock keybindings after selecting the clip).
You will also NOT be able to use the Track Select button or Ctrl All type selection methods. You will need to select the CLIP in the Parent Track(s) instead... otherwise you will also select the hidden clips in the lanes as well.
As I said... this is exactly why I generally create my comps and move them into a blank track so there is only ONE clip in the track to work with. Then I can go apeballs in the parent track without creating chaos on the clips.
It is also why I have been requesting "Archive Take Lanes" and "Hide Take Lanes" options that can totally remove lanes from system resources, view and editing actions instead of having to move comps into a new track.
I just thought of another way you could do this to guarantee your original clips don't get wrecked.
After you flatten your main comp that you will use for editing select all the other lanes (and all the clips in them) and lock their Pos/Data. That way as you mess around in the parent track on your mian flattened comp those clips don't get altered at all no matter what happens.
It seems you are going for a Block Arranger type workflow (which is another common request) and the only reliable way to do that in Sonar is to flatten your composite takes, isolate them for editing (away from the original takes) and work solely with those clips... which will then create new clips and lanes and whatnot that eventually need to be Bounced/Flattened.
This is actually how I've written quite a few things. I'll record a bunch of riff, bass parts, create drum loops/beats etc then split/copy/yank everything around until I get the arrangement I like.
Then I'll retrack whatever I need to once I'm happy with the arrangement (for MIDI stuff or audio looping type music I'd just make sure everything faded/looped together smoothly with X-Fades and whatnot).
Sorry, man... it's just the new editing flow. Parent Tracks just aren't designed for what you're trying to do.
If it's any consolation it took me about a half hour to really nail down how to work in the new paradigm and I personally prefer it in many ways. It just takes a little more prep work to work right on the parent track (and really since the original implementation of "layer/comp" type recording in DAWs many moons ago this type of editing crap has always been dicey at best).
Cheers.