Intercompanies inventory control table

[Uolsiec]

Table.PNG

Hi all,
i am preparing a intercompanies inventory transfer table.
Is there anyone can help to teach me how to verify the figure in this table?

Thanks!!!
p.s. of course, my table have much more items than the sample.

For example,
Factory1 gives 2 apples to Factory2.
I deducted 2 in the Factory1, C5.
And then, I added 2 apples to Factory2, D2.
The question is how I can ensure that I entered -2 in C5 and 2 in D2 by 1 simple formula or function in excel?


**********Sample File********
Sample.xlsx