scrypt and merged mining?

[lucasjkr]

Hey there. I'm wondering if anyone can help me find what I'm looking for, which is a scrypt-based coin with a shared blockchain/merged mining with Litecoin. Not 100% on how that works, some places I read that the merged mining is done as part of the coin (ie, when namecoin adopted a merged mining capable blockchain, they basically had to cut off transactions to their old chain and make sure they got to the new chain instead), while other sources seem to say that it's just a function that mining pool operators can choose to use or not? Any idea which way it goes?