Let's say I start with code that is
(c) 2014 Struvious Featherstone and licensed according to the BSD 3-clause license.
Now I make some changes for my employer Zippety Duda, Inc. and I want to publish them, with my employer's permission. What does the resulting license have to look like? Is it still required to say
(c) 2014 Struvious Featherstone? Or does Zippety Duda Inc. replace that? Or does the code now have to contain both?
And how can I determine this by looking at the BSD license terms?