Change Schema ID but Preserve Data

Is it possible to rename the schema id for a field without losing the already-trained data? For example, if I had a field with a schema id of "po_number" and I wanted to rename it to just be "po".

The API documentation says "In order to transfer annotation field values properly during the schema update, a datapoint's category and schema_id must be preserved." so it looks like the answer is "no". Is this correct?