I have:

One pillar already exists:

users:
  bob:
    home: /some/odd/place/bob
    setting_foo: blah
    setting_bar: 42
    password: [hash]
  
another is input, where some elements are present:

some_other_title:
  martha:
    home: /some/odd/place/martha
    setting_foo: mumble
    

i want to end up with:

users:
  bob:
    home: /some/odd/place/bob
    setting_foo: blah
    setting_bar: 42
    password: [hash]
  martha:
    home: /some/odd/place/martha
    setting_foo: mumble
    setting_bar: 42
    password: [hash]

so...

For each entry in my input:

  - If there's no item for 'password', I need to generate one using an existing randomizer ('salt "host" cmd.run' will do for me here,
      provided I know how to get its output into the pillar)
  - For other items, if there's already an entry ("setting_foo"), it shows up in the product, and,
  - If not, ("setting_bar"), I have a set of defaults to fill in.

The stuff about making a password is secondary; I can address that. The real issue is merging in the other stuff.