I just discovered this thread and read most of it. What a mess you've been involved in. It so peeses me off when they throw out that "it's a civil matter" over something like this. I once had to go take a horse back in the middle of the night because I couldn't get help from authorities when the buyer stopped paying and wasn't caring for the horse either.
Hopefully tomorrow you'll have your golden boy back home. What a good looking horse, and I hope he comes back to you in the same shape he left in. Situations like this make me wish for a little old fashioned justice. But it seems the ones who aren't doing wrong have their hands tied every which way.
I would take it to the limit on both of these guys, the kid who contracted to lease and the dip stick uncle who is trying to milk you for money to get your horse back.
Good luck, I'll be watching the outcome. And I applaud you on your patience, I wouldn't have been able to spend this much time trying to do things legally. Horse theft is getting big, my neighbor's one ranch away had it happen last week. They had two in the trailer, was loading up the third horse when they were busted in the act. All the horses being turned loose and given away, and idiots have to take what isn't theirs.
And don't let your knee hold you back. It took me two years but I got back in the saddle again, screws, pins and all in a left knee totally reconstructed. Although, a 16.3h TB is making it interesting on whether I need one attempt or two at getting up on him some days, LOL.