It is not possible to fool the Hue bridge into thinking a virtual device is real. It forms its own mini network with devices attached to it, so if they don’t send zigbee signals during the join to that network, they will not be usable.
In any case, I’m not quite sure how you are imagining using such a device to control other devices attached to the bridge.
If you are also using Apple HomeKit, there are some things you can do by creating a virtual Hue bridge and getting integration through HomeKit that way, but that’s bringing the SmartThings controlled devices into HomeKit rather than the other way around. And it’s a pretty technical setup.