title: `react-table` v7 how to preserve a grouping's sort order whilst the rows of the groups are sorted
body: <p>I have a table that is grouped with an initial sort order applied.</p>
  <p>I want to be able to sort on the UI but at the same time preserve the initial grouping sort order.</p>
  <p>So it would be like a multi-sort but that one sorting rule is always applied to the group.</p>
  <p>This is the initial sorting rule:</p>
  <pre><code>  const initialSortBy: Array&lt;RisksIdentifiedSortBy&gt; = [
      {
        id: DataAccessors.RISK_SCORE,
        desc: true,
      },
      {
        id: DataAccessors.GROUP,
        desc: false,
      },
    ];
  </code></pre>
  <p><code>RISK_SCORE</code> column would be sortable:</p>
  <pre><code>{
      Header: (): JSX.Element =&gt; {
        return (
          &lt;Box sx={{ margin: 'auto' }}&gt;
            {t('policy-management/summary:TABLE.HDR.RISK_SCORE')}
          &lt;/Box&gt;
        );
      },
      accessor: DataAccessors.RISK_SCORE,
      sortType: 'alphanumeric',
      Cell: ({
        value,
        row,
      }: DataTableCell&lt;RiskLevel&gt;): JSX.Element | null =&gt; {
        return !row.canExpand ? (
        ...
        ) : null;
      },
    },
  </code></pre>
  <p>And we would force <code>RISK_GROUP</code> to be sorted the same every time without being sortable itself from user interaction:</p>
  <pre><code>  {
      Header: t('policy-management/summary:TABLE.HDR.RISK_GROUP'),
      accessor: DataAccessors.GROUP,
      Cell: ({ value }: DataTableCell&lt;string&gt;): string =&gt; value,
      SubCell: ({ row }: Pick&lt;DataTableCell&lt;any&gt;, 'row'&gt;): JSX.Element =&gt; {
        const {
          original: { riskCategory },
        } = row;
        return &lt;Box sx={{ ml: '1.5rem' }}&gt;{riskCategory}&lt;/Box&gt;;
      },
      width: '20%',
      disableSortBy: true,
    },
  </code></pre>
  <p>Any ideas how to do this?</p>
  <p>I think it would be similar to programmatically setting the sort option in one column when another is sorted?</p>