OK, so here is the short version:

I was at the church today in the evening for confession (the church itself didn't have much to do with it). I the place where I go, normally a few people would wait quite a long time for their turn and in that time you could talk a lot with the others. So I come in and I see the guy I normally talk to there with one of the very few girls who are actually close to my age (I'm 21). I've heard about her plenty of good things and I'm like cool this may be my chance. So I get in and we talk and at one point I nonchalantly got her number in the middle of the conversation and I thought it was kinda smooth.

Next thing, she is talking that she does crochet as a hobby and the other guy points to her sister, who has a crochet thing on her head. so then her little sister joins the conversation and she is just about the purest creature I have ever seen. She is unbelievably cute and we kind of hit it off to the point where just the two of us are talking, effectively ignoring the other two, who got joined by a third person. The one whose number I got is a couple of years older than me, while her sister is a couple of years younger than me.

So now I'm just like, what the fuck do I do. Is there a way I can get in touch with the young sister without coming out as a total dick? Reddit, please help!