title: How to join different pandas dataframes stored on a list of dictionar ordered by multiindex
body: <p>I have a set of data in a list. Each item of the list is a dictionary with a unique key and the value of the dictionary is a DataFrame that contains 6 columns + index col.</p>
  <pre><code>    list = [{&quot;A&quot;: Participation    Assignment     Words   Creativeness   Innovative Great
       Date                                                        
       2021-01-02  95.00  75.00  75.00  79.00     100      OK
       2021-01-05  83.00  83.00  83.00  80.00     100      OK
       2021-01-06  98.88  78.88  77.00  77.00     34       OK
       2021-01-07  77.00  77.00  77.00  77.00     150      OK
       2021-01-08  79.00  79.00  70.00  70.00     99       OK
       ...            ...     ...     ...     ...      ...      ...
       2021-02-18  65.67  36.67  35.59  36.88     94       OK
       2021-02-19  60.94  38.00  36.94  38.72     75       OK
       2021-02-22  40.00  43.80  40.80  42.71     82       OK
       2021-02-23  42.00  43.81  38.99  42.29     174      OK
       2021-02-24  42.00  45.00  42.00  44.17     175      OK
       
       [1065 rows x 6 columns]}, &quot;B&quot;: Participation    Assignment     Words   Creativeness   Innovative Great
       Date                                                        
       2021-01-02  95.00  75.00  75.00  79.00     100      OK
       2021-01-05  83.00  83.00  83.00  80.00     100      OK
       2021-01-06  98.88  78.88  77.00  77.00     340      OK
       2021-01-07  77.00  77.00  77.00  77.00     150      OK
       2021-01-08  79.00  79.00  70.00  70.00     93       OK
       ...            ...     ...     ...     ...      ...      ...
       2021-02-18  65.67  36.67  35.59  36.88     94       OK
       2021-02-19  60.94  38.00  36.94  38.72     95       OK
       2021-02-22  40.00  43.80  40.80  42.71     182      OK
       2021-02-23  42.00  43.81  38.99  42.29     174      OK
       2021-02-24  42.00  45.00  42.00  44.17     75       OK
       
       [1065 rows x 6 columns]}, ...]
  </code></pre>
  <p>What I want to do is to have a large DataFrame where the general index is the Date, the first index Column is the respective key of each dictionary and the sub index of this is</p>
  <pre><code>      A                                                                               B
              Participation    Assignment     Words   Creativeness   Innovative Great   Participation    Assignment     Words   Creativeness   Innovative  Great
  Date
  2021-01-02  95.00            75.00          75.00   79.00          100        OK      95.00            75.00          75.00   79.00          100         OK
  </code></pre>
  <p>Something like that. Is it possible?</p>