One of the things you need to do to be eligible for Recognition of Tax Exempt status is to create (what the IRS calls) Articles of Organization. This document describes the organization, who is eligible to join, what the org can and cannot do, what happens to assets if disbanded and a few other things. Since the document must describe who is eligible to join, you can define that how it suits you.
For example, the Charter for my PTO says:
a. All parents and/or Legal Guardians of current Douglas MacArthur Elementary School students and all current paid employees of the Douglas MacArthur Elementary School are Regular Members of the MacArthur School PTO.
b. Regular Members have the right to attend and participate in all public meetings and activities of the MacArthur School PTO.
This covers parents, teachers, admin.
You can even put more restrictive eligibility rules for who can serve on the board. We limit board membership to parents who live in the town.
We are wanting to become a tax exempt organization, however, concerneds were voiced about this would not allow teachers who are also parents to vote at meetings? Does anyone know the answer to this question?