MERGE MINING REQUIRES THE SAME ALGORITHM FOR ALL COINS--

SiaCoin (SC) is mined with Blake2b algo, and Ethereum Classic (ETC) is mined with Dagger-Hashimoto.  They cannot be merge-mined.  With Claymore's miner, you can mine both coins simultaneously, but they are being mined with separate algorithms.  The calculations done for one coin are not used by the other coin, they are  separate.  

Merge mining applies the hash generated within one algorithm to all coins being mined.  A good example can be found at Give-Me-Coins.com, where scrypt algorithm is used to merge-mine a half-dozen coins in a single pool, and you can keep all of them.       --scryptr