My wife usually likes threesomes with my friends that are interested in her, that she's sure are gonna keep coming around.
First visit might be a bit dull actionwise cos it's mostly you tossing a comment/compliment or two to push the idea you are interested in her, and then pushing for hugging and kissing before you go. Shoot for the hug first so your arms are around her then it should be easy to get some long kissing out of her.

The key element is to make it seem like it's her own idea that threesomes start the second visit. So she has no clue it was preplanned. She hates being set up, but it's not too hard to make it look coincidental. Second visit will most likely be smooth to drift to the first threesome as long as we play the first visit right. If she seems horny enough as yous do the goodbye kissing, I'll slip behind her and help see if we can get her to do more before you go.