[chef] Chef steps and licensing

[Hedge Hog < >]

Hi,
I've noticed some Chef step files have the opscode copyright and
license header text, some don't.
Given I'm refactoring some/many of these steps, I wonder what should
be carried over in terms of licensing.
To wit.  A step gets split into a Cucumber step file and an API file.
The API file contains the logic - often different from the Chef logic
(e.g uses Aruba or custom methods) - sometimes following quite closely
the original logic.
The step description too is sometimes the same, different or just similar.

So the questions.  What do the various Authors and Opscode expect:
 - When the API logic is influenced by Chef's
 - When some of the step regexps are Chef's
 - When the original step file has no license/copyright text

Essentially the issue seems to be that 'portions' of a file have come
from, been influenced by the Opscode/Chef code.
Yet it doesn't seem right that I can take the license/copyright text of say:

# Author:: Adam Jacob 
(<
 >)
# Copyright:: Copyright (c) 2008 Opscode, Inc.
# License:: Apache License, Version 2.0
#
etc

and change it to arbitrarily assert that only portions of the file are
now Authored by Adam Jacob copyright by Opscode.

# Portions Authored:: Adam Jacob 
(<
 >)
# Portions Copyright:: Copyright (c) 2008 Opscode, Inc.
# License:: Apache License, Version 2.0
#
etc

That is, it seem I need to get their agreement.   And then the
agreement of anyone else whose authorship/copyright I come across?
Correct?

TIA

-- 
πόλλ' οἶδ ἀλώπηξ, ἀλλ' ἐχῖνος ἓν μέγα
[The fox knows many things, but the hedgehog knows one big thing.]
  Archilochus, Greek poet (c. 680 BC – c. 645 BC)
http://wiki.hedgehogshiatus.com