title: Merging changes after splitting a commit without mentioning the author name
body: <p>I was asked to split one big commit into multiple smaller ones in someones repository.
  So I forked the repository. Did rebase and made multiple commits.</p>
  
  <p>Basically at the moment I have  this on my side:</p>
  
  <blockquote>
    <ul>
    <li>smaller commit 3 [Author: A]</li>
    <li>smaller commit 2 [Author: A]</li>
    <li>smaller commit 1 [Author: A]</li>
    <li>some older commit [Author: C]</li>
    </ul>
  </blockquote>
  
  <p>While the original repo was:</p>
  
  <blockquote>
    <ul>
    <li>One huge commit [Author: B]</li>
    <li>some older commit [Author: C]</li>
    </ul>
  </blockquote>
  
  <p>What I would like do is merge the changes back to the original repo without mentioning "Author A".
  That is, the original repo should look like the original author did the splitting:</p>
  
  <blockquote>
    <ul>
    <li>smaller commit 3 [Author: B]</li>
    <li>smaller commit 2 [Author: B]</li>
    <li>smaller commit 1 [Author: B]</li>
    <li>some older commit [Author: C]</li>
    </ul>
  </blockquote>
  
  <p>What is the proper and/or the faster/easiest way to do this?</p>
  
  <p>If changing authors this way is not possible, what is the cleanest way to merge the changes without cluttering the commit history too much (we are using github).</p>