The key fact to understand is that you are not technically changing your PTA into a PTO. You are actually shutting down a PTA (one process) and starting a new PTO (another process). They're unconnected. Your new organization is the equivalent of starting a science club or a "parents of band mamebers" org at your school. Schools can (and often do) have multiple orgs like that in existence at the same time.
So the recommendation from here is to start the PTO process as soon as you want. Get your EIN. Get your bank account set up. And start getting some funds in there.
There is nothing at all wrong with doing that. It's certainly not "2 of the same organization". I'm not even really sure what that means.
- Rockne
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