they usually can speed the process up, and seeing as it's a child, they should be more than willing to help. (I had someone who worked with the agency who determines wether the disability is real or not, tell me that).
Here's two websites I pulled up:
http://www.disabilitysecrets.com/has tips and secrets on filing (that the ssa won't tell you about)
and:
How To Apply For SSI For Your Child
There are two ways to start the SSI disability process for your child. First, you can go to your local Social Security office and with the assistance of a local office representative, fill out the SSI application packet. You can also call SSA’s nationwide toll free number–1-800-772-1213. Staff there will interview you and send you forms to sign and take into your local Social Security office to complete the filing process.
In either case, you will be interviewed about your child’s medical condition, functional limitations, and treatment history. This information will be used to decide whether your child satisfies the SSI childhood disability standard. In addition, you will be asked about your family’s income and assets so that Social Security can determine if your child is financially eligible for SSI.. Finally, if your child is not a United States citizen, you will be asked to provide proof of his or her immigration status to see if he or she is eligible for SSI benefits. For more information on the childhood disability requirements, financial requirements and for what groups of noncitizens are potentially eligible for SSI, see the Childhood Disability, Financial Eligibility Requirements and Noncitizen Eligibility pages.
http://www.hdadvocates.org/ProgramsChildren/ChildrensSSI/howtoapplyforssiforchild.htmGood luck, it's hard... I hope you are able to get the help you need.