Well, that is kind of working against how AP works. Actually the reason for having the “clones” are exactly what you were trying to do with blanks.
So, you add and use the clone drawings (aka held frames) to do the timing of your key drawings. You can now keep the timing all the way through your work. So no need to delete anything and lose the timing. When you start to do breakdowns and in-betweens the clones will gradually be made into original drawings and the timing will stay the same all the way through.
Just stand on a clone and hit Clear Drawing, then it turns blank and you can draw your breakdown.
I can explain much more, if you want me to 🙂 I hope the above makes sense. Please let me know.
Thanks,
Niels