How to add field to a cloned TClientDataset

Question

I have

ClientDataSet1 > DataSetProvider1 > SqlDataSet1> sql = select * from customer

i add all fields at design time than i copy the ClientDataSet1 rename it to ClientDataSet2 On DataModule create event i clone the cursor

ClientDataset2.CloneCursor(ClientDataset1, True);

so the cloned dataset has now all persistence fields defined in cds1 according to the answer in this question i attempted to add extra field InternalCalc/LookupField to the cloned dataset at design time but error occurred during the execution "Field not Found"

My question what is the correct way to add extra field that doesn't exist in the master dataset nor in the database to a cloned TClientDataSet.

thank's ...