Net storage bin qty in WM

Folks,

Have a requirement to find the net bin qty in WM locations.

At any instance, the stock exists in 91* storage types n addition to the shelved stock say 001.

Ex.

For storage type 001- stock is say 100

For storage type 914- stock is say 90- (with negative sign).

So net stock for the storage location is 10.

Now the question comes to find by storage bin.

Within storage type 001, stock could be in multiple bins B1, B2 & B3

B1- 25

B2- 55

B3- 20

If a report is to be generated with the net stock, how should the calculation be done?

Out of B1,B2 & B3, which bins to be considered (& by how much), to come out with a net stock by storage bin.

Any thoughts?

Regards