True DBGrid Pro 8 or probably other grids

I'm trying to use True DBGrid Pro 8 but this question may apply to lots of other grids.

This grid is bound to an adodc control and works just fine for what I need, almost :). However I need to solve at least one more thing with it.

To make it as simple as possible for this question let's say I have 2 columns, one called previouslycompleted and the other completed. The user can only type in the completed column. When he saves it I need to have the completed column data moved to the previouslycompleted column data and if previouslycompleted already contains data I need the completed data added to it (both formats are currency) and I need the completed column returned to the default which is $0.00

Sure would appreciate any help with this

I forgot to mention I would need to do this for all rows that have a value other than $0.00 in the completed column