I forgot to mention a few things about this situation.
The Dad & the Mum of the 18-year old both seem to know she has a crush on me & also that I have the hots for her. Yet when she's come up in conversation they've always played it down, her Mum has witnessed her showing off boobs, thighs & ass to me at parties. She has scolded her occasionally yet when we talk about it, she just kind of shrugs her shoulders saying 'she's so grown up now, she does what she wants'.
One time me & the Dad were talking & daughter walks past, boobs spilling out of her dress again. I of course look, Dad catches me then gives me a little punch in the stomach laughing & saying 'I told her not to wear that dress but she insisted'.
I get brave & ask him can I say something without offending him? He says of course. I whisper in his ear 'She's got the [his wife's maiden name] boobs' (Her Mum & both aunts are total babes with huge boobs).
He finds this hilarious then says 'You should've seen [his wife] when she was 18!' (His daughter's age)
The other mother also knows her 19-yo daughter has a crush on me & that I want to fuck her badly. Yet she also dances around the situation, brushing it off by telling me 'she's the Mummy of the house now' & 'she's always had a thing for older guys, don't worry about it'
So far I haven't touched either of these girls but I hope that will change when they're in their mid-20's. As long as I can keep on good terms with the families.