I get how it is to be in this place:
my relationship, or lack of, is so fragile with him.
and how that changes the discipline options in play.
I think I also get -- and correct me if I'm off base here -- your desire of getting you, S15, and his mom all together in court. Getting third party eyes on the situation, shining light on what's going on, having everything out in the open, and maybe getting some consequences for S15 (and his mom)-- are those parts of what you want?
If I'm remembering correctly, counseling with anyone that Mom picks is a disaster, and hasn't been a healthy way for a third party to have eyes on the situation.
So, I get the draw to have a different, perhaps stricter, third party in play.
OK, so, if not "Mom's choice" counselors (too weak) and not going to court/having Master involved (too strong based on fragility of relationship)... OK, what can we think of here?
I think I've mentioned school involvement before -- if the photos involve classmates, that seems like a big deal and perhaps a liability for the school, so maybe the school has a disciplinary board or group. Can you talk on your own to the counselor at S15's school about your concerns and/or about "hypothetically what would happen to my son if X, Y, and Z"?
There's also having your own counselor/therapist (can't remember if you do or not) to "game out" some of these scenarios, figure out how far you are willing to go, what your fears are about the fragility of the relationship, that kind of stuff. DH has a lot of fears and anxiety about losing his relationship with the kids, especially his oldest (SD14), even though the relationship is a lot stronger than it was. He needs some space with our T for that work.
Group, what other "in between" options am I missing here?
Positive outcome for relationship/strictness for S15 scale, 0 lowest and 10 highest for both:
-Mom's choice counselor: 0/0 (not effective)
-scraps66 taking S15's phone: 2/2 (does show there are consequences, but no real change in S15 behavior)
-scraps66 working on own with his counselor: 8/3 (changing self can improve relationships, but no direct S15 involvement)
-S15 getting in trouble with school: 7/7 (could be a wake up call, and S15 has to deal with "non-dad" authority)
-getting both parents and S15 in court: 1/9 (scraps66 concerned about impact on relationship with S15)
other?
Juvenile law involvement? Some areas are cracking down on juvenile "sexting". That would be a severe wake up call, perhaps.
...
What are the positive things in your relationship with S15 right now?