In the sales order, we have main item and sub-items. The main item is a project item and it has a billing plan which gets copied from the project. Now the requirement is to copy the same billing plan(of the mainitem) to all its subitems- billing dates, billing type, billing rule, date category, percentage of the amount to be billed, etc. So that when we do billing for this sales order all the items and its sub items are copied in the milestone billing document.
The billing plan is not at header level since the sales order can have multiple project items and their milestones can differ.
Please suggest how to acheive this- coping of billing plan details from main item to all the subitems.