I don't see a problem with his handwriting for now except that he complains of pain, so I'm going to be working with him on building up hand/forearm strength a bit.
Before you spend much effort building up strength, take some time to observe how he holds his pencil, whether or not he seems to be gripping tightly, and his posture while he's writing. My dysgraphic ds had lots of wrist pain when writing before he had handwriting OT, but he had an odd pencil grip and he also hunched over his paper and held his wrist while writing - once he was taught a proper grip and how to sit while writing his wrist pain disappeared. His handwriting OT did include fine motor finger-strengthening exercises, which also seemed to help with control, but building up hand/forearm strength wasn't necessary and probably wouldn't have addressed the issue that was actually causing his wrist pain.
I don't want to quote the part of your reply that discusses the relationship between parents and school in case you want to delete it later, and I also realize you're a third-party in this equation so there's likely little influence you hold on this decision, but fwiw, it's easy sometimes for parents to get caught up in not exactly a battle, but basically being at odds with school for whatever reason (warranted or not). We dealt with an extremely inflexible school during our ds' early-mid elementary years, and had we stayed there, would have had to eventually resort to legal counsel - but the thing I learned from that is that sometimes as a parent you can get so caught up in the battle that you lost sight of realizing that the same amount of time and energy directed in a different direction can actually benefit your child more. We made the decision to take our ds out of his elementary school at the end of 5th grade - about the same age as your SK11. It wasn't only the best decision possible for him, but it also was a great decision for me (even though I didn't realize it until after we'd made the decision). My dh and I were caught up in the battle and I was spending so much time and effort just fighting that battle - which led to two huge issues: first, I didn't realize how much of my time and energy it was consuming, and second, my ds saw that we were basically at odds with the school, and he saw it as the school not being supportive of him (which it wasn't). His life was all-around soooo so much better just getting him (and us) out of that situation.
I only mention that here because it sounds like SKs' parents are very caught up in the battle, but they also appear to have some resources (as they are considering having you homeschool SK11, if I understand this correctly). They're momentarily not seeking a diagnosis because they don't want the school to know about it (also if I understand what you've written correctly). This seems to be putting the focus on the issues with the school, when the focus really needs to be on SK11 (and his sibling). If SK11 has issues or concerns that are pointing to needing an evaluation and/or diagnosis, it's not helping him to put it off while fighting with the school, and it's also losing an opportunity to obtain understanding which can help you (and others) in educating SK11. Sorry, hope that doesn't sound like I'm preaching or anything.... just a concern that my own family has gone through and having come out the other end of it (my ds is in high school now) - letting go of the battle with his public school and making the change for middle school was the single best thing we've probably ever done for him, aside from getting him accurate diagnoses so we had a good understanding of what his needs were and how to address them.
Best wishes,
polarbear
