The "Allocate stock" and "Unallocate stock" actions will allocate or unallocate available inventory to or from a sales order.
You can choose whether or not to allow partial allocation.
If this option is set to "Yes", any available items will be reserved against the order and will no longer be on hand in the warehouse to be allocated to other orders. Any unavailable items will be skipped.
Setting the option to "No" means orders will only be allocated when all items on the order are available.
Alternative warehouses can be chosen and prioritized if allocation should be attempted from other warehouses.
If partial allocation is set to "No" and all the stock is available somewhere else, the warehouse will be changed on the order and the allocation carried out.
Note that split allocation across multiple warehouses is not possible. A sales order can only be assigned a single warehouse.
Therefore it is not recommended to set both "partial allocation" and "use alternative warehouse" to "Yes".
If an order is already allocated or partially allocated, then it is not possible to create a second allocation, nor is it possible to change the order warehouse.
Therefore if you need to allocate additional inventory or change the order warehouse, you must unallocate the order first.
You can do this using the "Unallocate stock" action.