Ok, how about BTC+NMC address receives NMC payment for work submitted with original BTC address linked to new BTC+NMC address during establishment of merged mining.  Make a cut of date to stop back payments and you would keep the rest or whatever plan you have for them.  Not everyone is going to want namecoins.  I think a system has to be implemented rather quickly because when the next diff drops you will have more problem NMChilds to deal with.