I would actually consider that an improvement as it would allow for more flexibility.

But no, it looks like it still only cares about your two parents. What's it called again, when you divide something by two?

I guess you could stat your whole family tree and present your justification for your weird stats to your DM, but from what I can see they're just salty about the word 'half' even though they've done absolutely nothing to address the fact that their system isn't tailored to care about anything further back than one generation.