So my understanding is that you want any inconsistencies in the child part prices between the two sheets to be highlighted on the "AAA" sheet. This highlighting will then prompt you to manually update the price on the "AAA" sheet so that it is in line with the "A" sheet. Is that correct?
If that is correct, then there is a better way of doing it. Rather than having the child part prices in "AAA" as constants, you can use formulas which reference the "A" sheet. That way, if the prices in "A" are changed, those changes will automatically also be updated in "AAA". Does this solution interest you?
I don't understand what you want. What does "reflection through conditional formatting" mean and what does it achieve? If you want a change highlighted, would that highlight be permanent? If not, what should trigger the highlighting to be removed?
Reflection through conditional formatting will definetely help for eye estimation (i.e. means in which part[s]) where prices increased/decreased. And number of parts in the corresponding sheet may vary from 1 to say 30 or 40.
That will give a clear picture where price increased/decreased since last saved.