title: How can I set "IsSiteAdmin" property true for a user using Webservice/REST API for Sharepoint?
body: <p>I need to know how I can set <em>IsSiteAdmin</em> property to true for a user in my O365 setup using REST API for Sharepoint or any webservice for that matter. I can do this via Powershell but I'm looking for a solution through APIs. </p>
  
  <h2>Update 1</h2>
  
  <p>Sorry for being vague, the question actually is that whether or not an Admin (Company Administrator) assign a user(say himself) who is <em>NOT</em> a site user on a Site as Site Collection Admin for the OneDrive(my site) for other tenant users.</p>
  
  <p>Let's say that admin is <em>abc@mytenant@onmicrosoft.com</em> and there is a user say <em>pqr@mytenant@onmicrosoft.com</em>. The OneDrive(my site) for this user would be; </p>
  
  <pre><code>https://mytenant-my.sharepoint.com/personal/prq_onmicrosoft_com
  </code></pre>
  
  <p>Can I make abc@mytenant.onmicrosoft.com (who is NOT a site user on pqr@mytenant@onmicrosoft.com) a Site Collection Administrator on this site?</p>
  
  <p>Much appreciated!</p>