From your last statement, I can confirm you are just a PO. You don't even know that Supt is not a superscale rank! Either that or you are a civilian who is not familiar with the uniformed services ranks! Don't embarrass yourself by claiming that Supts are superscale ranks. Just go find the rank comparison chart in the SAR! If you are an SPO and don't know this fact, I can only shake my head! Your CEP is probably not that high!

Anyway, since you already said that the Supt is the CO then his designation/appointment is higher therefore it is totally possible for the two HTS who are civilians to be under his charge. Sometimes it's not about the rank, it is also about the designation/appointment. If someone has a higher designation or appointment, then he would be vested with all the power and authority of the higher designation or appointment. This is quite basic knowledge!

Try claiming that Supt is a superscale rank and most people in MHA will fall off their chair laughing at you! I'm just trying to save you from embarrassment.