Change the signing key in the backup node config to a new key, and then use a tool like https://github.com/witness-essentials/watcher to swap between active signing keys automatically when you miss blocks.

Another thing that would vastly improve the stability of the network is to just change your signing keys to STM1111111111111111111111111111111114T1Anm

You're now witness 7, and I'm 28. I should not be teaching you anything at this point.