def find_group_missing_numbers(squares: list, grid: list) -> list:
    """
    Gets the missing numbers from the group of squares

    :param squares: A list of tuples (row, column) coordinates of squares
    :param grid: The sudoku grid as a 3D list
    :return: A list containing all the numbers (1-9) missing from the box
    """
    missing_nums = [1, 2, 3, 4, 5, 6, 7, 8, 9]

    for square in squares:
        if grid[square[0]][square[1]][0] != 0:
            missing_nums.remove(grid[square[0]][square[1]][0])
    return missing_nums