Help create ILM policy

Good day! Please advice!
I have a couple of indices - filebeat-current and filebeat-old
I need to create ILM policy, which will copy data that is more than 7 days old from filebeat-current to filebeat-old. New incoming data should always continue to be written to the index filebeat-current. The index names should not change. Is it even possible?

ILM will not copy data between indices like that.

You could use ILM to use aliases called filebeat-current and filebeat-old, and then move the underlying indices between those.