Long-term vs short-term holder

I'm a long-term holder of ethereum as I've held shares of it for over 1 year. I did however recently buy some more about 3 months ago. If I were to hypothetically sell all of it now, would my broker separate the shares and put the portion I held as long term under long term section of 1099-B and separate the short term gains under the short term section? Or what if I just sold a couple of ethereums? How do brokers usually generate those statements for the same crypto?