grandpa = {'name': 'grandpa', 'parents': []}
dad = {'name': 'dad', 'parents': ['grandpa']}
son_1 = {'name': 'son_1', 'parents': ['dad']}
son_2 = {'name': 'son_2', 'parents': ['dad']}
relatives = [grandpa, dad, son_1, son_2]

def sortRelatives(relatives):
    # returns a resulted dictionary:
    # logic


result = sortRelatives(relatives)
print result

result = {'name': 'grandpa',
            'childred': [
                        {'name': 'dad',
                        'childred': [{'name': 'son_1', 'childred': [] },
                                     {'name': 'son_2', 'childred': [] }] }
                        ]

        }