Ability to derive PO line DFF value from a value on PO header DFF

We have a requirement to add service dates to our invoices which we've had to do via an invoice DFF. Now that we've switched to IDR it does not allow for touchless experience as AP team still has to enter service dates to the invoice via invoice header DFF. I saw that this is not possible to copy a DFF from PO header to invoice header (please confirm) but would it be possible to have the service dates on the PO header inform the PO lines DFF and copy the same service dates from header to the PO line? Then