Yes you did.
You left out the contents of that letter.
All you need to do is tell the school authorities to piss off and enroll your children and quote the letter:
Title VI of the Civil Rights Act of 1964, which prohibits discrimination based on race, color, or national origin, among other factors, by public schools. Also cite Plyler v. Doe, the 1982 decision by the U.S. Supreme Court that held a state may not deny access to a basic public education to any child, whether that child is present in the country legally or not.
Place of residence is irrelevant, if legal immigration status is irrelevant. Unfortunately, the masters at the Department of Education forgot to mention legal address, which is based on legal residency.
Funny thing is, when I moved here the schools were doing so well they were afraid of overcrowding. The best schools in the State are here. Now they're crying because our county is built out and there are no new children registering. They are losing thousands of students each year and none to replace them. Glad I've stayed long enough to see this.