Ok here goes......
1. Checking account opened years and years ago
2. Class reunion account titled "Blah Blah High School Class of 1962"
3. Used one of class members social security number as tax ID who by the way is not a signer on the account.

Question: Who owns the account? (Comment: We know way better now!)

I would say the signers "own" the account. I would change the tax ID to an EIN ASAP to avoid any additional issues. They can get an EIN for the group in five minutes if they go to IRS.gov and click on the Apply for an Employer ID Number link.

Good luck.

Dunno who "owns" it and would not offer an opinion...an authorized signer can write a check to anyone he or she wants to.