Suggestions:
In Sales order form can be used to create the schedule for delivery. We can split the Sales order form into multiple Sales orders, based on schedule despatch date, different Sales orders are created for that date. In the Sales Order despatch date is set as the due date for that order. On entering the total quantity, the system divides it equally amongst all the specified schedule despatch dates. We can also split orders Item series wise. Sales order type is allowed to select from dropdown. However it gets populated on the selection of customers.