I agree that handwriting (in a typical child) can change, but dysgraphia complicates the picture. Even in a dysgraphic child, handwriting can change. Our ds had 9 months of handwriting OT when he was 8 and the OT work corrected his pencil grip, improved his writing posture, eliminated hand pain when writing (at the time), and improved his handwriting legibility. The OT worked with him on proper formation of letters but it didn't stick. His legibility didn't improve further, it stayed basally at the level he came out of OT with even though ds got older and his peers' legibility kept improving. The pencil grip stuck. Posture didn't always stick, but we can remind him and he sits up
OT didn't eliminate letter reversals, punctuation errors, mixed up lower and upper case etc.
I also think it's important to keep in mind for kids with dysgraphia that even if their handwriting *looks* legible it can be very slow, and even more importantly, it's not truly automatic. Those of us without dysgraphia get to a point where we write without thinking about how we form the letters etc - our fingers simply learn how to do it. A dysgraphic person is going to have so much of their working memory continually focused on how to form the letters that they don't have working memory left over to adequately focus on other aspects of writing (both tasks such as punctuation/grammar/spelling and the content).
We're also living in a world where even parents of completely neurotypical kids are asking the question "why does the school spend so much time focused on handwriting when our kids are growing up in a world where they primarily type?". For our ds, there were just too many other things he needed to have a chance to focus on (both strengths and challenges) for us to lament too much over letting go of handwriting. He did learn cursive at school along with his 4th grade class, but halfway through sixth grade he realized he'd forgotten it (completely). He can sign his name, and I think that's important.
If you want to teach correct letter formation, there are many folks who recommend Handwriting without Tears - we tried it, and I think it might work for a child who doesn't have hand pain when writing and for a child who is willing to work on handwriting. OT is another avenue for improving legibility - but at 10 I'd be cautious about whether or not to do it simply because private OT can be expensive and there's no guarantee with a dysgraphic child that any of what is learned is going to be permanent.
I also was wondering if you see a pattern to when your dd becomes frustrated while writing (because you noted that she uses a conventional grip when relaxed). Sometimes kids with dysgraphia also have challenges with other aspects of writing - generating ideas, organizing thoughts, editing, etc. If there's a pattern associated with a particular piece of the writing process (outside of handwriting), working on it would potentially help reduce the handwriting issues. And the good news about those types of writing problems - they are easier (jmo) to remediate than the handwriting challenges that are due to dysgraphia.
Best wishes,
polarbear
