Hi M. - Dealing with IEPs and 504s can be a very large challenge for parents. The big part is to start educating yourself about the law and regulations around both of these. Also check with your state department of education's website, many times they will have the state's special education manual online for you to download, if they dont call them and they should mail you a copy for free. Each state is different but the Federal law IDEA and Section 504 are above each state's manuals.
In the state manual there should be a section that covers eligibility and the process to get on an IEP or 504 for your state. Depending on the specific district and state some 504s are suitable for students others you will want the extra safeguards that come with the IEP under IDEA. When you (and the eligibility team/school) look at your daughter and her needs, they will be looking at any test scores or evaluations that have been done. Many times a child will have a diagnosis but they still must qualify with scores, etc. That is where some of the below info can help you with this process in understanding scores and how they work.
The next place to start learning is www.wrightslaw.com, the best money I ever spent was on their combo with the "From Emotions to Advocacy" and the "Special Ed Law" book along with their WebEx Training. The training along with the books was like sitting in one of their conferences. It will walk you through the process as well as how to document communication, progress, test scores, etc. There are wonderful examples of how to write letters when dealing with schools.
When dealing with the school - have they looked at all areas that are affected by her disability? How does this work for her handwriting, is this hampering other areas of her education, how is her social? Look at all of these, write them and any concerns out. If the main area is fine motor (like with writing) then she may only qualify/need assistance with that area (usually with an OT, they may have 1:1 service or consultation). If there are other areas of concerns, make sure that the school is aware of them (using the Wrightslaw style letters).
I also suggest that you check with your doctors/hospitals to see if there is a local parent support group (for parents of special needs kids) in your area, they will be a great resource as well as support as you go through this journey.
Feel free to drop me a line if you have more questions about this topic. God Bless