*sigh* Yeah, she was very pretty. And sweet. I'll never understand why they just moved out and left her to roam the halls, but their loss was our gain

.
I forget that we have two entrances - the one into the building and then our condo. If Amy ran out the door, we still had one more barrier; I don't have the same worries as you. But, when Tash was a baby, I would take a squirt gun and wait out on the stairs for her to poke her nose outside the door. She was born outside, and an open door was something she would just walk through. But Kess was older and when I tried the same on her, she'd just lick the water off her fur and go on out

. But doing all that took patience, consistency and time, and I was home with a young child, so I could.
I wanted an older cat after Tasha - I just couldn't start all over again. Amy was six-years-old when we got her, and not very well socialized (you know how the novelty wears off with kids, and then the animal is just left to her own devices.) Now you'd never know she was the same cat, but I think having a quiet home with one other (who was ten years her senior), no dogs, no children and just two old fuddies like the Honey and me to spoil her, made all the difference. Btw, Siberians are said to keep their kittenish side for a very long time (very true, she's still playful at ten), and they're hypoallergenic (also true. I've had allergic people come over and they are surprised to find that they have no symptoms. So I'm plugging the breed, just a little.)
Anyway, you've got plenty of time, and just do what you're doing, it's so healthy. I still cry for Tashie every now and then *tears up* - she was my baby for fourteen years. I have a friend who was devastated when his twenty-three-year old calico died (never had an ill day; she just didn't wake up one morning.) When you've been a cat-staffer for that long, what do you do? And most people are still not all that compassionate when it comes to such a loss. They simply don't see the strength of that relationship, the sheer number of years, all those memories - pets are part of the family. I've been to the vet's office for a routine visit and seen roomfuls of people - as many or more than you'd see in hospital, at a parent's illness - waiting to say goodbye to some ancient buddy of theirs...
*MASSIVE HUG*