Need help doing background vocals

[wooden rune]

can someone help me with this?
I wanna know how to get an ai voice to work with the background vocals without the model having a seizure, some people managed to do it but I can't figure out how it’s possible

https://youtu.be/rVArWVydPLI?si=AH-N99lSoIel8zD0

This video for example

[still cobalt]

you just need clean vocals

and it should work just fine

to get perfect results like this