But what if nemstake owner splits his stake in two part (different NXT accounts), redeems one part now and another part later?
I dont's see solution for it now

It will be complicated for devs, I agree, but some clarification would be good. While we have approx. 3 weeks (correct me if I'm wrong), people still will trade Nemstake on AE, maybe making some profits if price go up

Also, need some clarification on whether we can send more than 2 NEM Stakes for redemption. It would be nice to get a message from the receiver account stating that the nemstake was received (like a receipt)
I think we will be able to come up with some clarifications on both of this questions tomorrow.