jgreene33:
However, once the drone reaches the end of the transmission range of the original transmitter.
I suspect you have a major misconception here which might be underlying (and undermining) your whole design.
The end-of-range will be incredibly vague. I doubt if you could define it to anything better that +/-50 metres, or maybe only +/- 100 metres. It will be different in different weather conditions and with different levels of interference from equipment you are completely unaware of.
To my mind it will be essential to operate the base station and the relay station on different channels (frequencies). - but I don't know if that concept exists with a HC12.
Conceivably you could have two HC12s on the drone each listening to a different channel but only one of them transmitting at any one time. But will the extra complexity to manage all that add to overall reliability ???
...R