Suggest that any thing above approx 15k has a different coloured dot and is detected at a range of aprox 1.5 the set distance.
Suggest that any formation (whatever its altitude) is detected at 1.5 times the set distance It would carry a slightly larger dot of what ever colour the altitude demanded.
This has some basis in fact and would provide a greater advance warning of high stuff (allowing defenders time to climb).
An earlier indication that bomber formations were inbound would allow the correct type of interceptor to be chosen.