title: How to merge 2 observables without breaking current subscriptions?
body: <p>I want to have a observable to which I could subscribe with the ability to merge other observables in runtime. </p>
  
  <p>I have thought of using the <code>Observable.Merge</code> method, but it returns a <strong>new</strong> observable sequence.</p>
  
  <p>so if I have:</p>
  
  <pre><code>var merged = observable1.Merge(observable2);
  </code></pre>
  
  <p>that will not allow me to dynamically merge more sequences. I would have to create and subscribe again to the newly created sequence.</p>
  
  <p>Is there any way to merge and keep the current subscriptions untouched?</p>