...

point.py

class Point:

    ref = None
    operator = None

    def __init__(self, x, y):
        self._x = x
        self._y = y

    @property
    def x(self):
        if self.ref:
            return getattr(self, self.operator)(self.ref[0].x, self.ref[1].x)
        return self._x

    @property
    def y(self):
        if self.ref:
            return getattr(self, self.operator)(self.ref[0].y, self.ref[1].y)
        return self._y

    @x.setter
    def x(self, v):
        self._x = v
        self._y = self.y
        self.ref = None

    @y.setter
    def y(self, v):
        self._y = v
        self._x = self.x
        self.ref = None

    def __add__(self, other: "Point") -> "Point":

        point = Point(0, 0)
        point.ref = (self, other)
        point.operator = "_add"
        return point

    @staticmethod
    def _add(x, y):
        return x + y

    def __repr__(self):
        return f'{self.x},{self.y}'


A = Point(1, 2)
B = Point(1, 3)
C = A + B
print(C)
A.x = 0
print(C)