I love weddings

My wife's half sister Emma is her dad's baby from a late marriage and as such she is 14 year younger than my wife and 16 years younger than me. She looks nothing like my wife who is short and very average built, Emma is tall, Slim and stacked, Not super pretty but...
We went to a family wedding and the to of them got trashed and then Emma disappeared, My wife asked me to go look for her before we headed back to the hotel and I found her out behind the hall, She was sitting very close with another wedding guest from the other side of the wedding and they were talking very closely, I told her we were leaving and she asked me to give her a couple minutes and she would meet us out front. Well as per usual she wasn't out front and I went to find her again, I walked around the corner and she was out back with a dude, She and the guy were standing and they were talking, I told her we were leaving and she said she would find her own ride so we left.
While laying in bed listening to my wife snore I heard the door to Emma's room open and close, We had adjoining rooms so I could hear a little better than a normal room with a full wall between, I laid there and listened as I heard giggling and drunk whispering which is louder than normal talking LOL. I got out of bed and opened the door on our side between the rooms and listened closely, It was just me and my wife in our room and her mom had taken all the kids from the reception back to her room which as the plan so she had two double rooms which were also adjoining so me and my wife could drink and not have to deal with kids.
I listened carefully at the door and could hear kissing and giggling etc. I couldn't make out if it was one female voice or two but I was actually assuming it was the dude from the wedding who was one of the groomsmen, I thought for a long time before I made a decision I closed our blinds and made our room as dark as I could before going back to the door to listen, I could hear muffled sounds but they sounded far away, I tried the handle to her room and it was unlocked, I carefully opened the door to her room and right away heard the shower running but nothing else and thought whoever else had been there must have left.
The bathroom light was on and the door was partially open so I thought if nothing else I could catch a peek at Emma naked in the shower so I stepped into her room, I tip toed up the the bathroom door and was just about to look into the bathroom when I heard a female voice I didn't recognize, I leaned forward and the sight in front of me was beyond what I had hoped, As I looked in Emma and the girl from the wedding were both naked, Emma was stepping into the shower so I could only see her from behind, Long legs, Tiny ass and the other girl was definitely shorter but had a decent ass and looked nice as she stepped in right behind.
Unfortunately they closed the shower curtain so I couldn't see anything but I could hear them kissing and moaning and then I heard the shower shut off and was like "Hmmm, Do I stay here and watch them get out or run?", I made the smart call and bolted for the door, I closed Emma's door 90% of the way and ours the same, and then waited in the dark, I watched the other girl come out of the bathroom and she looked quite nice, Biggish boobs, Big, Hard, Dark pink nips, Shaved bald and a pretty brunette, My wife' half sister stepped out but turned off the bathroom light as she did so I didn't see much, The lamp beside the bed turned on and from where I was I could only see the foot of the bed, Emma was out of sight but the other girl came into sight a couple times so I got to see her ad then Emma walked past, The two of them seemed very comfortable being naked and I got to see Emma from behind as she walked up to the other girl and then it was on, They started kissing and then Emma turned her around and pushed her down on the bed, Now Emma was standing fully nude and I could really see her well, Long legs, Shoulder length brunette hair, Her huge tits looked great, firm, Big pale pink areolae and flatish nips, Flat stomach and just a racing stripe of pubes, She climbed on the bed and I could only see their feet and legs so I carefully opened our door a bit then pushed hers open slightly until I could see the bed, Emma was on her hands and knees, The other girl had her legs spread and Emma kneeling between them, Emma looked great, Tiny ass, Light pink pussy lips, Just a little bit of light pink inner labia sticking out, Her butt hole was on display and is light pink and looks tiny, Th other girl lifted her legs and wrapped them around Emma's waist, Emma spread her knees and I could see the other girls pussy, Darker pink, Very little if any inner labia sticking out and a dark pink butt hole.
I couldn't believe I was watching my wife's little sister hook up let alone with another woman, I watched Emma slide down and lay between the other girls legs reaching up and tweaking her nips, The pair of them look great together and I watched a lot, Face sitting, 69, Licking, Kissing, Fingering and both cumming multiple times (also twice for me) before they finally laid down and snuggled, I didn't think I should risk closing the door at that point so I left it and tip toed back to bed. I was laying there thinking I got away with my little voyeur episode and just the I heard the other girl say "Was that door open the whole time", Emma said "Fuck me, I don't know...I hope their door is closed", the other girl said "Who's room is that?", Emma said "My sister" and then I peeked as Emma opened the door and peeked in, Quietly closed the door and the one on her side.
I finally fell asleep but then was awoken by my wife saying "We're late...Get up, We're late....Go wake up Emma" and she bolted to the shower, I walked to the door between our room, I opened our side and grabbed Emma's door handle not knowing what I would find o her side or even if it would be unlocked, I tried the handle and it turned, I opened the door quietly and oh man, What a sight, Emma was laying on her back, The other girl snuggled up with one leg across Emmas one leg leaving her dark pink pussy and asshole fully exposed, Emma had one arm above her head and the covers twisted around them leaving Emma's big tits exposed and her other leg out to the side leaving her pink pussy also exposed.
I thought for a minute about what to do.
Option #1...Wake Emma up letting her know I seen her naked and in bed with another woman.
Option #2...Leave her and let my wife wake her up so she could see the whole situation.
I went with option #3...Let y wife wake her up but follow my wife and get the best of both worlds.
I laid back in our bed and waited...My wife got out of the shower and said "HEY....Did you wake Emma?", I said "Oh fuck" and jumped up, My wife headed for the door between our rooms muttering away and opened the doors, She stepped into the room and stopped, I was right behind her and she just froze. It had o be a solid 10 seconds of just standing there before she backed up and backed right into me, She turned around and looked at me as I surveyed the scene, My wife tapped me n the chest and motioned back to our room, I stepped aside and let her pass, She grabbed my arm and I looked at her, She scowled and mouthed "OUT".
I backed out staring the whole time and then she closed the door, I could tell she was in shock and then she looked at me and said "Well....That's um...Ya", I nodded my head and she said "Well...If you ever wanted to see Emma naked your wish was granted", I nodded my head and my wife said "What?", I said "Oh come on...You can't even be pissed...That' a fuckin impressive body", My wife said "Ya, ya ok...She does have an impressive body...Go knock on the door". I knocked loudly a couple times and Emma opened the door, I was about to say something and then my wife blurted out "We are already late...Let's go" and jut then her "friend" bolted for the bathroom, Emma realized we just seen a naked girl go past and dropped her towel, Emma said "Fuck...Ok, Sorry" and my wife said "We already know...Just get ready...We have to go".
If Emma's face could have been more embarrassed I don't know how, she closed the door and my wife said "Oh...Oops, Sorry, I shouldn't have said that", 20 minutes later the 3 of us walked to the lobby without a word, Got in the car, Drove to the airport and it wasn't until we were seated waiting for our flight that Emma spoke, She said "Uuuhhh...What did you mean by we already know?", My wife cleared her throat and looked at me then at Emma and said "We came into the room to wake you up before that", Emma just nodded her head and said "You came right in?", My wife said "Yaaaa...Uh...We both did", Emma looked at me and said "You too?", I nodded and Emma said "Uuuhhh....How much did you see?", My wife blurted out "Everything". So needless to say Emma was extremely embarrassed and very quiet on the flight home.
Overall it was a great trip and hopefully some day I get to experience something even close to that again but I doubt it.