I do not believe that they would post the "original miles", as those miles relate to a flight that was voluntarily changed.

If the passenger was required by the airline to travel on different flights, meaning that it was the airline's fault alone that the OP couldn't travel as originally booked, then sure, original routing credit should not be a problem; however, as the new flights are a result of the passenger's own request, the full consequences of that choice should be borne by the passenger, who requested them. (Maybe if the flights were cancelled prior to the passenger's request to rebook; otherwise there should be no reference to the original flights for mileage earning purposes).