def update_dictionaries(final_dict: dict, new_dict: dict) -> dict:
    """
    Merges two dictionaries by including key/value pairs or adding values to corresponding keys from a dictionary
    (new_dict) to a target dictionary (final_dict).

    Parameters
    ----------
    final_dict: Dictionary, which should be updated.
    new_dict: Dictionary, from which the update values are obtained.

    Returns
    -------
    final_dict: Updated dictionary.
    """

    for key in new_dict:
        if key in final_dict:
            final_dict[key] += new_dict[key]
        else:
            final_dict[key] = new_dict[key]
    return final_dict