We can understand the work process of the extension with the below given example.

Let’s Suppose we create a warehouse attribute. In this warehouse attribute, we create various options like warehouse A , warehouse B and warehouse C. This warehouse attribute is assigned to our used attribute set. We create products and assigned requisite warehouse. Now a customer has placed an order with 5 products

a. Product A belongs to Warehouse B

b. Product B belongs to Warehouse A

c. Product C belongs to Warehouse A

d. Product D belongs to Warehouse C

e. Product E belongs to none of warehouses

In this case , our order will be split into 4 different orders:

a. Order 1 having products of warehouse A, i.e Product B and C

b. Order 2 having product of warehouse B, i.e Product A

c. Order 3 having product of warehouse C, i..e Product D

d. Order 4 will be of none of the warehouses, i.e Product E.

Note 1 : Advanced Split Order On Checkout will work with the Magento default payment methods that is Cheque / Money Order and Cash on Delivery. In the case of any 3rd party payment gateway, it may need some customization if the third party payment gateway code does not follow the default Magento payment module pattern.

Note 2 : Extension works well with Simple and Configurable products and not with Downloadable and Virtual products as these do not have any shipping associated with them.