welcome in the forum!
in general BorgBackup is highly customizable but the AIO version might be not… You miss the idea of AIO if you try to fiddle with the system. AIO is designed to be highly standardized system with little to no configuration. I would sort your request into the category of advanced user who is not the audience of AIO.
I would suggest to adopt your backup strategy and use built-in AIO backups or don’t use AIO and built your own customized system…
@szaimen - do I miss something?