Stores Balance

My database is such where I have Stores at each location. Firstly how
do I initialise a store such that it shows 0.00 if there is no stock.

Then from say Store1 - This store receives stock from another store
such that its balance increases and at times, transfers stock (out) so
its balance decreases.
Similar for other stores.
I've done a query and put on a form so that it updates the balance
everytime through requery.

But this only works if there has been a transfer from and transfer to
done.

I would like it to also show if such that only a transfer from is done
or transfer to is done and not both.

Please help