I've been trying to follow but I'm lost. I can't figure whether you're compaining about
allocating hash to coins in the multipool or merged mining. They aren't related.
A clear problem definition would help.
NO FLAG TO SET MERGED MODE MINING--
I mine lyra2v3, and it features 3 coins. VertCoin (VTC) has a solid value, the other two are less valuable by at least an order of magnitude.
If I set "mc=VTC" in my password string, I mine VTC, and accumulate shares for VTC while waiting for a block. If I do not set a mining coin (i.e. "mc"), the pool directs my hash to any of the three coins, but not necessarily to VTC. I loose out on VTC shares when mining the less valuable coins.
If there was a merge-mining flag, "mg=VTC/HANA", or just "mg" to merge-mine all merge-mineable coins within an algo, I would accumulate shares on VTC at the same rate as if I were mining only VTC, and still receive shares for the merge-mined coins and earn BTC for payout.
Apparently, YIIMP portions out hash based on difficulty. The less valuable coins often have frequent blocks, but it may take more than a day of mining less valuable coins to equal the value of a single VTC block, which currently has blocks found every few hours.
Not all coins and algorithms support merge-mining. VTC was designed for merge-mining. SHA256 and Scrypt allow merge-mining. More earnings could be mined by the miners if merge-mining were a flag option at the pool. I don't think the pool would loose any earnings, likely it would gain earnings with a greater coin turnover on the market. --scryptr