Ya Gotta Wonder
The answer is, apparently, that they get crafty and devious. But reality usually has a way of breaking that façade down over time as increasing numbers of incongruities aggregate and coalesce.
As a for instance, I have the money orders for both Ninjas, filled out by me, along with the return receipts for the certified mailings of the money orders, also filled out in my handwriting. I can show a bank statement where I paid for the money orders on my debit card, from my account. I can show a history of one of the bikes on insurance I pay for, as my own motorcycle. I can show payments on my bank account for a shop manual for my own bike, as well as some parts. I can also show that Eradea left my key for my bike on my desk, and actually added an additional one to my desk when she was going through my desk and taking things.
I can show the LED bar I bought in order to make an extra LED brake light for the bike (it's mounted on the bike but not connected). The bike has a $400 HID headlight that's mine, also. But perhaps the most telling single item I have here that only makes sense if that bike is mine is that I had this made a year and a half ago, and hadn't gotten around to putting it on the bike yet, because it would require cutting the wiring for the UV license plate mount bolt lights and then re-soldering and sealing them once the item was in place on the bike. This has been on my desk for over a year now. She didn't take it, and it wasn't on her desk. She didn't take the factory shop manual, or any of the spare parts for that bike, as she would have done if the bike was actually hers (never leave spare parts behind, and if the bike was hers she'd have known which parts went to the bike, and that they were there at all).
I hope this John character sees the truth of these things before he ends up in a whole lot of trouble for having trusted her. Because she's not shooting straight with anyone right now, very clearly. And sadly, when the police come for the stolen trailer and the other stolen things, whoever has them on their property will get bracelets along with Eradea. I hope John is not that stupid.