<Snipped quote by Dirty Pretty Lies>
I was totally going to answer this and I forgot to.
It's possible that they'd never see each other. @impervious Daniel and Gabriel see each other on occasion, if Daniel ever has anything that needs a more... physical touch. Or if he just needs a more investigate view on a case.
But, yeah, depending on where they live in New York City, or New York state—it's a huge city and a huge state, so it's entirely possible to know they live there, but never see them.
Regardless, I might compile a list of where everyone lives? Or maybe not, since that might not be relevant to the story.
Any additional info is good fluff and fact-checking.