I needed a way to share one DataObject type between multiple has_many relations on the same page without the DataObject knowing how many links it had, this solution works using `AddNewInlineButton` and `GridFieldEditableColumns`. To add an additional table the only change required is another entry in the foreach on line 13.

EditableTablePage.php

<?php
class EditableTablePage extends Page {


  private static $has_many = [
    'TableRows' => 'TableRow'
  ];

  public function getCMSFields(){
    $fields = parent::getCMSFields();
    Requirements::customCSS(".col-Table { display: none; }");

    foreach ([1 => 'One', 2 => 'Two'] as $number => $name) {

      $displayFields = [
        'Column1' => 'Column One',
        'Column2' => 'Column Two',
        'Column3' => 'Column Three',
        'Table'   => function () use ($number) { return new HiddenField('Table', null, $number); }
      ];

      /** @var GridFieldConfig $tableConfig */
      $tableConfig = GridFieldConfig::create();

      $tableConfig->addComponent(new GridFieldButtonRow('before'))
                  ->addComponent(new GridFieldAddNewInlineButton('buttons-before-left'))
                  ->addComponent(new GridFieldSortableHeader())
                  ->addComponent(new GridFieldOrderableRows('SortOrder'))
                  ->addComponent((new GridFieldEditableColumns())->setDisplayFields($displayFields))
                  ->addComponent(new GridFieldDeleteAction());

      $gridField = GridField::create(
        "FeesTable{$name}GridField", 
        "Table Rows", 
        $this->{"Table{$name}TableRows"}(), 
        $tableConfig
      );
      
      $fields->addFieldToTab("Root.Table{$name}", $gridField);
    }
    
    return $fields;
    
  }

}

TableRow.php

<?php

class TableRow extends DataObject {

    protected static $db = [
        'Title'     => 'Varchar(255)',
        'Column1'   => 'Varchar(255)',
        'Column2'   => 'Varchar(255)',
        'Column3'   => 'Varchar(255)',
        'Table'     => 'Int',
        'SortOrder' => 'Int'
    ];

    protected static $has_one = [
        'Page' => 'Page'
    ];

    private static $summary_fields = [
        'Column1' => 'Column One',
        'Column2' => 'Column Two',
        'Column3' => 'Column Three',
    ];

    protected static $default_sort = 'SortOrder';

    //...

}