Aliens and heritage in character generation

At the moment, you roll to see if you’re non-human before determining your heritage. Not all the heritages have alien options, so I was wondering how people handle this?
I had a few different thoughts

  1. Roll to see if you’re an alien after determining heritage, if you’re a heritage with aliens
  2. Roll 1d7 for Ariadna, PanO, Nomands or ALEPH if you are an alien (ALEPH has a lower chance)
  3. If you’re an alien, pick your type of alien, which automatically determines your heritage.
  4. Allow any alien for any heritage?

Also, is the Nomad’s needing a 20 to be an uplift instead of a 19-20 like the others intentional?