Thank you, Peter, for this detailed answer.
In my case, I have decided to leave everything as it is. It would be relatively easy to take the female out – if she were the “sinner”. It is impossible to take the male out when he guards a clutch – and it would bear all the risks you listed. So I have to resign myself to having a pair which will not produce any offspring.
I now have this single young. Once I have identified it’s sex I can try to find a partner and see if this leads to fry of nagyi in my tanks at least.