Good Morning!,
I would like to know if there is any way to change issue parent massively. I have tested the import by CSV, which creates parent - child issues and binds them, but if they exist, it does not update its parent.
I have also investigated if it could be done using the REST API but I have not seen the way.
Finally, I searched for an add-on in the marketplace with no luck.
Can someone come up with a way to do it? I need to correct some 1,500 issues and doing it by hand will take a long time 
Thank you very much!
A greeting.