After some thought and and feedback, you and Samantha decide to go with tweaked House Flies. You would become female and she, male. With some basic knowledge
The suggested "Safe-traits" package would be used, so you wouldn't die except from the most thorough and sudden of methods, and recover very quickly. It was still suggested you would do your best to survive, as the main point was living until trial. Just in-case, you could control your immediate toughness and recovery in-case you wanted to play dead or know something really bad is coming. In the case of being House Flies, you and Samantha would be in aging stasis and would just be prime adults of each sex.
The "Beginner's Animal Adjustment" is used to conveniently know how to use the body with some ramp up time. Tweaked from past Witnesses' feedback, it avoids the trauma of fully dealing with an animal's brain, instincts, and sensory changes while giving a short ramp up time to give some flavor. The end result would be you fully conscious and knowing how to use your body as well as any real House Fly, with no instincts feeling like they were back-seating or actively riding you like a horse-jockey.
Now came your personal tweaks. It was Samantha that suggested the gender change, but you wanted to make sure there would be sex and kinks would be fun. Sex WILL feel good, and your libidos would be above average on top of whatever normal biology and mating behavior House Flies have. If there was sexual juices involved, including semen, there would be more of it. Finally you decided that you would above average egg production and would continue to produce eggs regardless of fertilization or not. You learned that female House Flies had a more limited reproduction cycle and you were a bit of a oviposition fetishist, so you tweaked that accordingly.
For some other tweaks, you were both "large" as far as House Fly sizes went at the suggestion of the Marshals with animal dominance issues and bullying. You could telepathically talk to each other and anyone else within proper distance, but took active concentration to do and maintain it. Otherwise, for all intents and purposes, you and Samantha would be normal House Flies other then all the tweaks.
At agreement of all parties, both you and Samantha were put into a sleep, unaware of how the technology actually works. You would next wake up as female (you) and male (Samantha) House Flies.