Siofra noticing your succubus affection is just a fun little reference from someone who can see/gauge spirits, not a bad thing! And yes, you only get that line if you are banging one or both succubi. I thought it would get people's attention and showcase her perception.
I love Sarah and Ashley, I love all of the girls rally, but Sarah is the one I'm probably most down bad for. Her or Selendis.
Succumilf isn't toooo far off now, but will be a bit different than each. She's a sweetheart tho.