import json


def load_signatures(signatures, file_path):
    """Load signatures from json file.
    
    Args:
        signatures (dict): Signature dictionary, which can be empty.
        file_path (str): The location of the json file containing a signature dictionary.
    
    Returns:
        dict: The update signature dictionary with signatures from the json file.
    """
    with open(file_path, 'r') as f:
        addon = json.load(f)
    for k, v in addon.items():
        offset_signatures = signatures.get(k, {})
        offset_signatures.update(v)
        signatures[k] = offset_signatures
    return signatures