Do you want to list all records from Internal in one portal and all records from translation in the other?
With such a set up, you could drag and drop the id UUD to id_Internal to do what you describe.
That would be great - though how do I do "drag and drop"?
Make sure that drag and drop is enabled in Preferences. Select all contents in one Field (triple click, enable "select entire contents on entry"....) Then drag to the other field.