So, in Martian Manhunter #3, we see that there is in fact another (still alive!) green martian on Earth, who was masquerading as Sara Moore. If I'm not mistaken, nothing else came of that story arc. So when D'Kay D'Razz, the newest alive green martian in the DCU, shows up, shouldn't J'onn still remember that there is another still out there, and not be so perplexed when he sees D'Kay???  
 
If that made absolutely no sense, what I'm trying to ask is: 
1. What really happened to Sara Moore/Cay'an? Is she still out there somewhere? Wouldn't that mean there are at least three green martians alive, not just J'onn and D'Kay? 
 
thanks:)

Well, the mini-series reveals that all but Cay'an are actually White Martians (probably left over from JLA's nemeses) telepathically convinced that they are Green to trap J'onn. As sometimes happens, if a series doesn't get read, it may not make it into continuity.

Much like Supergirl, Krypto, and the Phantom Zone criminals are with Kryptonians, Martians can pop out of the wood work in any number of ways.

Tomasi is usually up on J'onn J'onzz stories, so I'm surprised him missed Cay'an as a reference.