Dear Max,
thank you for your response. I am in doubt, mainly because I will somehow compare (as I mentioned) 1-patient-vs-all-HC in the end. So, technically, If I will make group response from all patients and all HC, my group response will be affected by epileptic patients that are not included in a statistics (I hope It’s clear) … but calcutation of separate group response and separate analysis on 30+ different subsets (each time one different patient and all HC) sounds like pretty time and space consuming idea 
So I will most probably stick to the group response calculated from HC.
Thanks for your time!