Migration is successful.
Steps are as per below:
1. Disconnection the network cables from Backup VRRP cluster in IPSO-390 appliance.
2. Connect the cables to Backup VRRP cluster at 5600 - Gaia appliance.
3. Reset SIC and fw unloadlocal and SIC is established at backup VRRP cluster.
4. And, perform above 1-3 steps in Master VRRP cluster at 5600 - Gaia.
5. And then, Get topology, version at cluster object.
6. Push down the policies to Cluster object. but Push policies is failed.
7. But, manage to resolve the issue after follow-up as per below kb. And, all of VRRP cluster are up and running and policies are able to push down the cluster object also.
VRRP cluster members are in "Backup/Backup" state
Thank you, everyone in this post!