We are having many troubles with Zoho CRM on Stock Management. 

- We changed some names and added some status to the possible Status of SO and PO. 

- Now, the stock management has gone crazy. 

If we create a S.O., it increase the quantity in demand of the product (good). But if the product is in stock, and we create a sales order from stock, it still increases the quantity in demand of the product (bad). 

Afterwards, when the S.O. is marked as "delivered", the quantity in demand doesnt go down (or the quantity in stock). 

The same for PO, quantities ordered / in stock do not vary well according to status. 

I expected to be able to cuztomise the rules of quantities updating according to status of SO and PO, thanks to workflow field updates rules. So i upgrade everyone to "Enterprise" version (35$ from the old professional, 12$...) 

However, these customisations are not possible ! 

Please explain how to solve this. 

Thanks 
Augustin