Not able to create a PO adding Header level DFF and line level DFF in that single payload

Able to create a PO in a single payload having headers, lines, schedules and distributions.

However not able to create a PO adding Header level DFF and line level DFF in that single payload for that header level DFF and line level DFF need to pass another API.

As per business requirement we need to have one API call for PO create along with DFF.

Thanks.