user47800: I know the title is a little obtuse, let me try to explain: 
I am trying to create a library of simple functions for use with my TFT Panel.
The Panel has an include file (#include "SSD1306Wire.h")
I have a sketch and I have the above #include file referenced in the sketch
I also want to use my library tftHelper.h but that library needs to reference SSD1306Wire.h as well to get the helper functions to work.
Is there a way to reference SSD1306Wire.h one time and be able to use the reference in the functions in my helper library?  
I guess, more importantly, what is the proper way to handle a situation like this?

user337: The proper way to handle this is to have an #include guard in the header file to prevent the content from being included more than once.
In your header file filename.h you would add something like this:
#ifndef _FILENAME_H_
#define _FILENAME_H_

// Your header code here

#endif /* _FILENAME_H_ */

The #ifndef block will prevent the code from being included more than once. Best practice is to always put include guards in header files.

47800: <p>I know the title is a little obtuse, let me try to explain: 
I am trying to create a library of simple functions for use with my TFT Panel.</p>

<p>The Panel has an include file (<code>#include "SSD1306Wire.h"</code>)</p>

<p>I have a sketch and I have the above <code>#include</code> file referenced in the sketch
I also want to use my library <code>tftHelper.h</code> but that library needs to reference <code>SSD1306Wire.h</code> as well to get the helper functions to work.</p>

<p>Is there a way to reference <code>SSD1306Wire.h</code> <em>one</em> time and be able to use the reference in the functions in my helper library?  </p>

<p>I guess, more importantly, what is the proper way to handle a situation like this?</p>
 337: <p>The proper way to handle this is to have an <a href="https://en.wikipedia.org/wiki/Include_guard" rel="noreferrer">#include guard</a> in the header file to prevent the content from being included more than once.</p>

<p>In your header file <code>filename.h</code> you would add something like this:</p>

<pre><code>#ifndef _FILENAME_H_
#define _FILENAME_H_

// Your header code here

#endif /* _FILENAME_H_ */
</code></pre>

<p>The <code>#ifndef</code> block will prevent the code from being included more than once. Best practice is to always put include guards in header files.</p>
