M.W.
You did not say what was the diagnosis which requires the therapy, so my answer will be general.
If your children are in school, and this is a disability that is covered under the Individuals with Disabilities Education Act (IDEA), and if the therapy is deemed to be necessary for their education, the school system MAY provide it. They may provide using their staff, they will not reimburse you for your private therapist unless they have refused to provide the service or if what they provide is not effective.
You also did not say if they were already identified with the schools and already have an Individual Education Program (IEP) or an ADA Section 504 Plan.
To learn about your rights under these acts, and to get some good practical advice on having your children evaluated and getting the process started, this is the best web site on the net:
http://www.wrightslaw.com/
If you have more questions, please feel free to message me.