Modifying the MIT license for modified source code?

Question

I have made a large number of modifications to some MIT-licensed source code to tailor it to the requirements of my project. Since this is JavaScript (for a website) the minified source code is naturally attainable by anyone viewing the site.

Whilst I am happy for people to use the source code under the terms of the MIT license, I feel that the body text of the license may lead to confusion since this is a highly modified version.

Is it acceptable to amend the license text? What is the correct etiquette ?

Original Text:

The MIT License (MIT)

Copyright (c) 2009 - 2014 Adriana Palazova
http://www.adipalaz.com

...

Full license in question (for a jQuery accordion control): http://www.adipalaz.com/docs/mit-license.txt

Proposed Change:

Add my name to the copyright notice in the MIT license:

The MIT License (MIT)

Copyright (c) 2009 - 2014 Adriana Palazova, 2014 {{My Name Here}}
http://www.adipalaz.com

...

And then change the header in the minified JavaScript file to the following:

/*! 
 * Nested Accordion (Modified by {{My Name Here}})
 * Copyright (c) 2009, 2010, 2011, 2012, 2013 Adriana Palazova
 * Copyright (c) 2014 {{My Name Here}}
 * Licensed under the MIT (http://{{My URL Here}}/mit-license.txt) license.
 */

Answer 1

Yes, what you're proposing with an additional copyright line would be fine.

Remember that copyright != licensing.

The license is the permissions others have in using a given work.
The copyright indicates who owns the intellectual property associated with creating the work.

In this case, you have made non-trivial modifications to the project so you are allowed to assert copyright over the work for the portions you modified.