Hi Arun,
Please try to use Bill Of Materials for your case.
Have two different materials -
HEADER MATERIAL 1: (10101) Physical product (With Stock) - Item Category with Billing Relevance as "A" and the item category will have delivery possible. - Actual Delivery of your material
SUB ITEM 1 - MATERIAL 2 (10101001) : One - A Dummy material (No Stock) - Item Category with Billing Relevance as "I" and the item category will not have delivery possible. - Perform your Milestone Billing with this material.
SUB ITEM 2 - MATERIAL 3 (10101002) : One - A Dummy material (No Stock) - Item Category with Billing Relevance as "I" and the item category will not have delivery possible. - Perform your Milestone Billing with this material. - DELETE IT IF NOT REQUIRED in the sales order.
Please let me know for any further clarification.
Regards
