title: Filter populated listbox and keep multiple selections
body: <p><strong>Context</strong></p>
  
  <p>I have developed a maintenance schedule for a production department in our company. As an extra addition we want to register which spare parts they use and how many. There are four machines in this department. Each machine has its own maintenance schedule made in Excel. </p>
  
  <p><strong>Description application</strong></p>
  
  <p>I have made a external central list which I open by <code>Set myData = Workbooks.Open("Hyperlink")</code>. This list contains all the spare parts for the machines. I have made this list external because the operators of the machine also need to be able to add extra parts. 
  I then populate a listbox with all the spare parts from the external list. When the listbox is populated I close down the external list, so that someone else can open the list. The image below shows what the userform looks like. The listbox is now filled with dummy products because I am still testing it. </p>
  
  <p>The operators of the machine need to be able to select multiple spare parts.</p>
  
  <p><a href="https://i.stack.imgur.com/w3X4Z.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/w3X4Z.png" alt="Userform"></a></p>
  
  <p><strong>Problem</strong></p>
  
  <p>I want the operators to be able to filter the listbox and at the same time select multiple spare parts. This is where it gets tricky. </p>
  
  <p>I know how to filter a listbox, but my way resets the listbox each time which consequently makes it impossible to select multiple product. I have looked at some other topic on stack overflow, but they have the same problem. </p>
  
  <p><strong>Question</strong></p>
  
  <p>Is there a way I can filter the listbox, select an item, filter again, select another item, filter again, select again another item etc. etc. ? 
  *Filter the populated listbox without having the source sheet open</p>
  
  <p>Thank you in advance. </p>
  
  <p><a href="https://stackoverflow.com/questions/42879261/how-to-filter-listbox-values-based-on-a-textbox-value/42880069#42880069">This topic needs the list to remain open and resets the listbox eache time</a></p>
  
  <p><a href="https://stackoverflow.com/questions/46230496/filter-only-matching-results-in-listbox-excel-from-textbox-text">This topic deletes all the items from the listbox</a></p>