Pytest: Calling super() within inheritted class fixtures

Question

I have a lot of similar groups of tests and would like to make a more general parent test collection as a class. In the class, I'd like to group the fixtures as well, but in some child classes I need to alter the fixtures slightly.

Something like TestCase2 below:

import pytest


class ParentCheckClass:
    """this parent test class is never run, it's a template"""

    @pytest.fixture
    def settings(self):
        return {"a": 1, "b": 2}

    def test_for_a(self, settings):
        assert "a" in settings

    def test_for_c(self, settings):
        assert "c" in settings


class TestCase1(ParentCheckClass):
    @pytest.fixture
    def settings(self):
        return {"c": 3}


class TestCase2(ParentCheckClass):
    @pytest.fixture
    def settings(self):
        return super().settings().update({"c": 3})

TestCase1 works as I expect: test_for_a fails.

TestCase2 throws the error:

Fixture "settings" called directly. Fixtures are not meant to be called directly,
but are created automatically when test functions request them as parameters.

Is there any way to do what I want?