Our kids are alike in many ways--and ex-difficult child doesn't have a lot of kids with whom he shares many commonalities.
I am almost CERTAIN that his dislike of reading as a child began as "internal noise" that either distracted him OR increased his anxiety due to content and was directly related to his MOOD DISORDER, rather than the Learning Disability (LD) or ADHD drum the teachers were beating
He always tested well on the WJ Reading Mastery Test BECAUSE (in my opinion) it is a unique test and does not replicate reading tasks in the classroom. My ex-difficult child could score very well on the nonsense decoding (forgot the name of the subtest, I haven't given a W-J RM for about 10 years) and even his passage comprehension was OK because it is only a long paragraph. Plus, in a psychologist's office, ex-difficult child would be adrenalized which would suppress the "internal noise" and increase his attention to task.
How this played out over the years substantiated my beliefs: the child who "could not read" (according to his classroom teacher in 2nd grade--but who tested at or above grade level) had read directions to put toys together that were written for adults when he was in KDG. Granted, there were diagrams, a strength for difficult child, but still--he could extract meaning from text with no problem. Example two: Music scores come with introductions about the composer and ex-difficult child was so ahead of himself in music that the stuff he was reading about the composers with no problems was written far above his tested grade level. I argued with the school (backed up by my own IE AND their testing), that ex-difficult child could not be Learning Disability (LD) in one situation and not in another--it is just not possible. OBVIOUSLY, his performance was fluctuating based on environmental demands (hating school didn't help) but even more on his MOTIVATION to do a task and the internal noise caused by the reading material.
How this evolved further is ex-difficult child refused (rather than saying he could not do it) to read about the bombing of Hiroshima and Nagasaki because it is too upsetting to him. He also refused to read Night which is a staple for 8th graders in our SD. By this time, the SD personal could clearly see the ED and exceptions to both assignments were granted after his psychiatrist stated that they were necessary due to risk of exacerbating suicidality. SHEESH--you would think they could figure this stuff out themselves.
My point is I doubt that your difficult child#2 can "develop" an Learning Disability (LD) at this point in time. Her academic performance can certainly be affected by many factors and she needs accommodation and support but to me, that is not the same as having an Learning Disability (LD) that is present from an early age. To some, the interventions might be the same so the diagnosis does not matter. This is not true in my opinion with bright kids with mood disorders. It is very empowering to my ex-difficult child to know that his teachers were wrong, he was right, and if he wants to, he can read anything but often prefers not to due to lack of motivation. My ex-difficult child has enough residual differences to cope with without having a mis-diagnosis of Learning Disability (LD) to make him anxious. He remains "different" but if that is confined to mood and motivation (over which he has some control due to insight and maturity) he is much better off emotionally. Being better off emotionally comes back around to "internal noise": the more positive his mood, the less distracting internal noise even today as a college sophomore.
I rarely talk about this stuff because I do not want to bore others with anecdotes that I usually think pertain to the differences (not disabilities) of my ex-difficult child. However, in many ways, your difficult children have similar issues. Therefore, I would look carefully at the possible side effects of all medications AND/OR "internal noise" causing difficult child#2s "ADHD" My ex-difficult child could look VERY distracted in real life (and still occasionally does) while testing in the 99.9% for the attention-concentration factor of the WISC-III. It's always better to have an ability than not have it BUT there is no guarantee that a kid with a mood disorder will use what he/she has. I guess there is no guarantee anyone will, but when you add in adolescence, middle school, and a mood disorder, the chances of performance problems that are not underwritten by a "permanent" Learning Disability (LD) or ADHD greatly increases in my opinion. If my weird experiences with my non-Learning Disability (LD), non-ADHD academically underperforming, sometimes distracted but also gifted and mood disordered child can help ANYONE, it makes my day.
Best to you,