What is Joint Account for FBAR?

Hello,
We filed our first FBAR this spring but used only one form as we assumed our UK accounts were joint. We are now questioning this. Our Current and Access Saver accounts are definitely joint with same account number, but our bank suggested we each open "Monthly Saver" accounts to build credit in each of our names. They do have different account numbers from each other, and to make it worse, only last one year and we've subsequently started new ones with new account numbers. We didn't think of these as separate because they're all at the same bank and sort code, but now see the potential problem.
If we should have filed separate FBAR's, can we amend and/or add a new FBAR for my spouse? I don't suppose accurately reporting all the account numbers on the original form counts for anything? Would the 15 Oct deadline still apply if we need to redo?
Thanks Very Much

My wife and I are in a similar situation where we have a joint checking account and individual savings accounts. Every year we each file FBARs, and both include the joint checking accounts in our forms.

We’ve not had to file corrected FBARs so I don’t know the process first hand I’m afraid.

It looks like you just send in a new FBAR marked as amended.

https://www.taxesforexpats.com/articles/fbar-fatca/how-to-fix-common-fbar-mistakes.html

The instructions for the FBAR state that if a person finds they gave inaccurate or incomplete information on their FBAR submission, they are required to amend the FBAR. FinCEN Form 114 has a box to check that FBAR is amended and another box to enter BSA ID of the original submission. If the error is discovered after the statute of limitations has expired (six years), it is not necessary for the filer to fix the error.

It is important to carefully consider whether or not to file a delinquent or amended FBAR if it is done outside of the various penalty relief options the IRS provides since it does not provide any protection from penalty. The IRS can still levy penalties if later it is determined that the error was caused by negligence or willful behavior. Conversely, the law does not allow penalties if the mistake was because of some kind of reasonable cause (that is, an honest mistake). Under the penalty guidelines of the Internal Revenue Service, even errors not determined to be reasonable may have only a warning letter issued at the discretion of the IRS.