Approvals process for Delivery document

Hello Experts,

I have a non conventional scenario, that needs to be handled by SAP Deliveries (Created without reference). Business scenario is as follows:

A research organization has multiple testing sites across the globe. It already has SAP system installed for its day to day processes. The organization has testing sites across the globe which order specific chemicals from a primary site. Now it is required to capture the delivery related part of this process needs to be mapped into SAP. SAP Delivery document would be used to meet this requirement.

However, the legacy system has an approval process in place. i.e. there are 4 lines in a request, it is quite possible that these 4 materials have 4 different 'owners'. These 'owners' 'approve' the release of specific chemicals in the legacy system.

The requirement is to map this line item level approval in the delivery document. However, Delivery Block is only at header level. Please provide suitable pointers so that this can be captured in standard SAP, or if not possible suggest appropriate customisation.

Thanks in advance,

Onkar