Cost Allocation based on PO line freight charge

Summary:

The requirement is as follows:

When multiple POs are shipped via single ASN ,GTM to do cost allocation of freight and insurance from Header to Line but based on the Freight value present on the PO for that particular PO lines.

For Example -PO1 has 2 item lines and 3rd line is Freight and 4th is Insurance (service Lines). Freight value is 10USD and Insurance is 5USD

PO2 has 3 item lines and 4th line is Freight and 5th is Insurance (service Lines).Freight Value is 150USD and 50USD

GTM would only receive 160 USD as Freight and 55 USD as Insurance. Ideally when we run the cost allocate GTM will allocate the Freight charges across all the 5 items of both POs with the base as 160 USD but the requirement is to allocate 1st 2 lines with the Freight as 10 USD and next 3 lines (2nd PO) with 150 USD.