Ask HN: experience enforcing the YC Open-Source Sales Agreement?

YC generously offered their YC Open Source Sales contract, which we've used as a base template for all of our client relationships.

Recently one of our clients was acquired and their parent company doesn't seem to believe they've inherited this contract. I don't see provisions in there for kill fees or for arbitration. I'm curious if anyone has had to enforce this contract and what their experience was?

(Ours is an exclusive relationship with a big upfront investment on our part, hence why I feel we'd have to enforce it.)