I wish we could

just kidding. Not that I'm aware of... the times that i've had seating change between on-line seat selection and boarding have been due to aircraft change, seating someone next to a special needs pax on request, and once due to an air marshal seating...so happens to PM's too.
That said, if someone knows the URL on delta.com for PM's to move seating around, please fwd the link

:all winks & smiles: