what I understood from your reply is once we reach the restore points with forever forward incremental, VBR creates a new Full backup + incremental chain for specified restore point and delete the old chain, Am I right?
No, new chain will not appear. Forever forward incremental method
keep using only one chain. Please check the hyperlink.Backup copy job
by default uses forever forward incremental backup method. Think of it how of reverse incremental chain, but with full backup in the beginning, not end of the chain.
If you want to keep on secondary repository last 30 restore points, just set retention=30 with no GFS retention.