Unfortunately TeamUnify does not have a way for divorced parents to have separate accounts/logins/passwords connected to the same children. This scenario could potentially cause more problems than solutions and we want to ensure we minimize double entries or deletion of entries of swimmers.
We suggest the parents get a shared free email account to be used for swimming only, such as from Gmail or Yahoo. This allows them to share the same login email and password for SwimOffice and thus both be able to sign up their kids for events, see their meet results, and sign up for jobs, but not share any other areas of their lives outside of swimming.
It also allows them both to place a credit card on file for potentially taking turns paying for dues. While this does mean either one could delete the other's card or use it to pay for team and meet fees, they could not use the card for any website or store outside of TeamUnify, nor could they see the entire credit card number. As a Super User, you can even check the Disable the Remove Card functionality in Billing Setup if desired to prevent that conflict; see the first article below.
Once parents understand that the information really relates to their children only they seem OK to share the account.
For parents who insist that that is not an option—that they MUST have separate accounts—then only ONE account can be connected to the kids. The account not attached to the kids can still login, view upcoming meets, sign up for jobs, etc. but they will not be able to sign up their kids for meets, view their results, nor pay for invoices.