Cost of a resource - by: VERGES

We have assigned a resource of a project with his cost field not filled in.
A real work alocation has been made by this ressource with a cost = 0 €.

Now, the Project Manager has assigned a cost to this ressource. But the economy of the project is false because the old real work allocation was based on a cost=0€.

Do you know if it is possible to make an update fo the project in order ton integrate the cost of the ressource for the old real work allocation??

Thanks,

Pascal