Community cats missing (Steel Lake, Federal Way)

My sister and I were adopted by a cat colony (we've gotten 47 cats fixed so far) and recently a handful of our long timers have stopped showing up and we're worried about them. These ones especially ALWAYS stuck close to our backyard, some for as long as three years, and are not prone to wandering. We would love any help finding them - just having them disappear is pretty devastating. We live in the neighborhood just east of Steel Lake Park in Federal Way, near 28th Ave S and S 309th St. Thanks in advance.