Store the Current value of datatable column in a variable
Concatenate it with the new string you want and assign again the new value to datatable column.
e.g
is this what you are looking for?
Concatenate it with the new string you want and assign again the new value to datatable column.
e.g
Code:
PrevValue = Datatable("String",dtlocalsheet)
ToAdd = "efg"
NewValue = PrevValue & ToAdd
Datatable("String",dtlocalsheet) = NewValue