This is the correct way to transfer the index definition to NewTable, however, the IndexDefs property of Table may not be up-to-date so you need to call the Update method of Table's IndexDefs property prior to its assignment to NewTable as shown in this example:

   NewTable->Active = false;
   NewTable->DatabaseName = "DBDEMOS";
   NewTable->TableName = "Temp";
   NewTable->TableType = ttParadox;
   NewTable->FieldDefs->Assign(Table ->FieldDefs);
   NewTable->Table ->IndexDefs->Update();    // Do an update first
   NewTable->IndexDefs->Assign(Table ->IndexDefs);
   NewTable->CreateTable();