I based the schematic on this data sheet for a db3 diac:
They (nor ST) don’t have a real schematic symbol so I used the one from the test setup down the datasheet. If eagle’s is better by all means go for it. Mine was a quick hack to satisfy the request.
You can’t. At present each variant needs to be in a separate part. Different variant name/numbers can then select between them in Inspector based on family (and sometimes magic in the source).
Peter