Mypy error while creating dynamic class from classmethod

I am creating a dynamic class from an abstract base class. Here is a simplified example.

from abc import ABC
from typing import List, Type

class IParentClass(ABC):
    _children: List['IParentClass'] = []

    @property
    def children(self) -> List['IParentClass']:
        return self._children

    def add_child(self) -> None:
        self._children.append(self._create_child()())

    @classmethod
    def _create_child(cls: Type['IParentClass']) -> Type['IParentClass']:
        class DynamicChild(cls):
            pass
        return DynamicChild

class RealChild(IParentClass):
    pass

rc = RealChild()
rc.add_child()
rc.children[0].add_child()
rc.children[0].children[0]

The code works, but Mypy gives me two errors (Variable "cls" is not valid as a type, and Invalid base class "cls") on cls in _create_child.

I could ignore the error, but I was wondering if there is a better way to manage this.