One idea, but I haven't tried it out yet.
https://github.com/apmuthu/frontac24/pull/7 allows service costs to be wrapped into purchased item costs on a single P/O or direct invoice and offers three methods for the calculation.
Thus, using the example offered, each computer is $100 and 10 computers are ordered. A Freight service item for $100 is added to the P/O, and using the Quantity method, the price of the computer is automatically recalculated to $110 and the service item is zeroed.
While this does not directly address the issue of wrapping in P/Os from multiple vendors, such as DHL, it may be possible to do this by leaving the P/O open until the DHL bill arrives:
1. When the DHL bill comes in, add the freight to the original P/O, which is then incorporated into the item pricing as described above.
2. Because now this overstates the amount payable to the vendor of the original P/O, when the P/O is invoiced, the Freight account must be added as a G/L item to the invoice using the negative amount of the DHL payment.
3. The amount invoiced should now be correct for the original vendor.
4. DHL is paid in the usual manner against the G/L Freight account.
5. The net Freight expense is zero, because the negative amount on the invoice offsets the positive amount of the DHL payment.
Result: the cost of the DHL freight is captured in the item price and will be reflected in COGS when the item is sold.
The disadvantage of this approach is that the P/O had to remain open to wait for the DHL freight billing, which delays deliveries, and therefore may not be acceptable.
I wrote the pull request to operate on the P/O, but perhaps it would preferable for it to operate when the invoice is created, which should work because item prices are not firmed up in FA until then. That would allow the delivery to go forward before the DHL freight bill was received.