Actulally, I think that you may be able to hear FWFD Station 27 only on the frequency of 855.9875. I dont know if it works though.
I lived in Hurst and can tell you exactly how it worked 4 years ago. Unless it has changed since then, Hurst contracted with Fort Worth for E27 to cover the SE part of Hurst, and Station 27 was actually a Hurst fire station.
Hurst dispatched E27 on the Hurst frequency. E27 would notify FW Fire Alarm Office on FDCH1 on the FW system that they were responding in Hurst.
If they got a call for FW, they would notify Hurst dispatch that they were responding to FW.
FW FAO also had a Hurst radio. Sometimes they would screw up and dispatch calls on the Hurst FD channel.
They were supposed to build a new Station 27 in Fort Worth, but I don't know if it ever happened.