Control content located in external html-file inserted through object tag into main site (index.html)

I am working on a project. It is a dashboard based on d3.js.

The following problem occurs:

There is the main site (index.html) that contains the navigation menu. I use various dashboards which are inserted into index.html via "object tag".

I looks like this:

<div id="sales1">   

    <div id="right">

    <object id="dashboard1" style="width:900px; height:600px; type="text/html" data="dashboard.html">
    </object>
    </div>

</div>

Within the dashboard-file (dashboard.html) it is possible to change the datasets (parsed csv) via button:

  <!-- here are the buttons to control the two csv data sets -->
  <button id="d1">Data 1 (should be units FTP 2018)</button>
  <button id="d2">Data 2 (should be units FTP 2019)</button>

<!-- The event listeners for buttons -->  
 <script>
    // here are the event listeners to control the buttons
    d3.select("#d1").on("click", function(d, i) {
      data1();
    });
    d3.select("#d2").on("click", function(d, i) {
      data2();
    });

</script>

Since I want to control this from the navigation menu on the main site (index.html), there must be a way to place buttons and event listeners to the index.html and change datasets within the dashboard from the navigation menu.

So the index.html should look something like this:

Buttons
to change datasets within dashboard.html
  <button id="d1">Data 1 (should be units FTP 2018)</button>
  <button id="d2">Data 2 (should be units FTP 2019)</button>

Event listeners
to change datasets within dashboard-file(dashboard.html, embedded through object tag) 
<script>

?????

</script>

    <div id="sales1">   

        <div id="right">

        <object id="dashboard1" style="width:900px; height:600px; type="text/html" data="dashboard.html">
        </object>
        </div>

    </div>

I uploaded the whole code here:

The main site (index.html): https://codepen.io/robx360/pen/wbpoQM Dashboard (dashboard.html): https://codepen.io/robx360/pen/pmpNWN

In the end, there will be various dashboards. By clicking on data 2019, datasets inside the dashboards switch the dataset to 2019 instead of 2018.