Is it possible implement optional capability or union type capability?

I’m implementing boiler controller integration(STSC).
It provides abstracted features from number of boilers.
But some boilers can set temperature as 3-level(High, Mid, Low) and others can set as an integer.
In this case, how can I make a proper device profile?

Should I add both (slider and heatingSetpoint) and ignore one?
Or make two different device profiles?
Or can I make a corresponding custom capability?