Hi Jim,
You shouldn't have any trouble with that combination of fish. Chromis can sometimes be unpredictable and refuse to school or even develop a pecking order with the strongest eliminating the competition. Certainly not always though, and when they do school, it's great to watch.
Regardless of how the Chromis act with each other, they shouldn't bother the Watchman or the Gobies. Just hope that the watchman hangs out up front.
Alice